In addition to all of the above, life is, among other things, a narrative. Every time we tell others about our past experiences, dreams, purposes, or mindset, we are telling a story, since we do not reproduce dialogue or thought directly, but use reported speech and cohesive devices to connect the parts.

One interesting thing that happens in the case of past experiences is that two or more people who have lived the same event and then retell it will probably render it in a different way. This is due to two main reasons. One is that parts of the event failed to get stored in long-term memory, and the narrator unconsciously bridges the gaps with fictional material that makes sense within the parameters of the story. The other is that those who shared the experience focused on certain details and overlooked others, so their memory, even if truthful, is dissimilar.

Why do we tell these particular stories? Because we may be  seeking confirmation, approval, sympathy, and/or opinion. For human beings, the only species endowed with language, the need to share -i.e., to tell- seems compelling. 

I think we all tell stories to make sense out of our lives.  Sharing stories allows us to understand the human experience and find ways to relate to and connect with one another.  Telling stories gives us a sense of culture, history, and personal identity.

Storytelling passes on personal, hi-stoical, or cultural events or experiences so they transcend to shared experiences. Storytelling alters individuals,changing them into families, groups, communities, and even nations. Storytelling can heal or encourage or motivate or perpetuate, depending upon the community need a nd depending upon the storyteller's intention.   

Storytelling serves to codify the values of a culture, explore the conflicts faced by populations and individuals, and examine the nature of personhood within a specific cultural context. 

That's one way of boiling an answer down to a few talking points. I think these points are important though and not just "pat" responses because, whether you are the storyteller or the listener, the story represents an attempt at expressing identity. Identity is a large and rather obscure notion, increasingly so the more you attempt to look at it directly. Storytelling offers an indirect way to engage with our ideas of who and what we are as people. 

Storytelling enriches the lives of those listening, is a great form of entertainment, and appeals to audiences of all ages.   Sometimes whole histories of nations and peoples are told through storytelling, the stories often being told with great humor or warmth.  Through the words and actions of a gifted storyteller, we are transported through time and space to another world!  For a few minutes or hours, our world fades away and we become part of another one.  We laugh until our sides hurt; we cry with the sorrowful and tears run down our cheeks.  We feel, we dream, we love, we hate!  It is a much-needed respite from the crazy, hectic, fast-paced world in which we live.  And when we return to reality, we are refreshed, renewed, and enlivened.  We can go on!

Another value of being a storyteller is having the opportunity to relive past experiences and perceive new insights in the process of telling the story again. As different audiences react in different ways, the events may be viewed from different perspectives, which can result in deeper understandings of the significance of the action.

For hundreds of years, storytelling was a way for cultures to maintain their history. If a village was large enough to be able to support a scop (storyteller), that person would record important events, births, battles, etc. Strangely enough, for such a time-honored position within the community, the job was not limited to men: a man could pass the job along to his daughter.

The traveling scop was a source of entertainment, especially in a castle, when the nights were long and cold. If a traveling storyteller was worth his "salt," he would have enough stories and/or songs to last him (or her?) many nights, ostensibly providing for his food and shelter until he ran out of "material."

This job and its importance is described in John Gardner's Grendel, with the presence of the Shaper, an old blind man who can "shape" the way people see and remember things through his words. Even in the epic poem Beowulf, the grandeur of storytelling is evident in the grandiose way the story is told, like an exciting story of war and valor, told by a scop.

And, finally, in today's world, storytelling can be the passing of stories of our childhood or the lives of our parents and grandparents, etc., which not only preserves the lives of those in our past, but promotes the use of imagination, something that I believe is in jeopardy with children who become so entrenched in the world of technology: game playing instead of "pretending" is a real loss in today's society.

Storytelling takes different forms and has different purposes depending on the time and place.

As noted above ancient storytelling was how communities were formed, how traditions were passed down, and how beliefs were shared and transfered to the next generation. We still do this in the form of bedtime stories and books for our children. Storytelling is also entertainment and education. Read any modern children's book and you will likely find fun, along with a moral.

Storytelling also exists to share our individual and collective stories with others. In earlier times it was through oral tradition, but today that same tradition continues in books, magazines, newspapers and online. We tell stories to enlighten and amuse, but also to share what we know and to share of ourselves. Before the digital age storytelling in both oral and book form was the only way people knew and learned of those people and places outside their own lives.

Historically, a major purpose of storytelling was to create a community.  People had no shared written history in those days.  Therefore, a major way to create a sense of unity among them was to tell stories.  As people were all exposed to the same stories, they came to have a common tradition.  This held them together as a community.

Storytelling serves a variety of purposes and motives.  One reason for storytelling is to capture a moment or event and immortalize it; this was certainly a primary motive in ancient times with the great oral traditions of storytellers.  Storytelling can also be used to explain occurences or events that we do not understand, like in the ancient greek, roman, and native american mythology. 

The most important aspect of storytelling that unites all of the motives is, of course, to entertain.  Storytelling should have the ability to transport the listener to another time or place.  A story that fails to capture the listener's imagination becomes just another boring lesson. 

What are the purpose of stories?

I also think that storytelling is a means of finding meaning in and imposing order on the chaos that is life.  When we can create a narrative of our lives or the lives of real or fictional others, we are able to believe that there is purpose in life, that things happen for a reason, that there is a plan. Thus, in some ways, storytelling and religion serve the same purposes.  Jung posited that we all have a collective unconscious that is the repository of stories and archetypes and that we each "star" in these stories in some way that acts them out, each of us adopting a role in the stories.  Either way, our language reveals our deep need to perceive life as a tale, when we speak of having a "happy ending," for example or refer to a "chapter" in our lives.  Even supposing those cave paintings were intended to record actual events, they are still stories, since a story is meant to select the details that serve a purpose and impose some order and meaning upon the anarchy of existence. 

What are the purpose of stories?

There are a number of reasons why stories have been told over thousands of years, and in different formats and styles.  Story-telling has been around virtually since the dawn of man. Cave drawings intended to describe events represent the earliest known instances of such communications, although such efforts are believed to have been intended primarily to report events that actually occurred.  Over time, however, storytelling evolved to include the conveyance of information, both fiction and nonfiction, through oral means, through paintings, music, dance, and through use of the written word.  Why individuals thousands of years ago -- and it is believed that Homer wrote his epics The Odyssey and The Iliad as far back as 800 B.C. (or, B.C.E.) -- decided to conjure up fictional tales and present them in myriad forms, including through plays, narratives, fairy tales, musical lyrics, and other means will never be known.  What was the purpose in writing or telling stories?  We really don't know.  What we do know, however, is that storytelling developed and evolved at least in part to help explain natural phenomenon that mystified earlier civilizations.  No where is this truer than in the development of mythology, especially by the ancient Greeks, who explained celestial observations through reference to theology.  Formations or constellations of stars were said to depict events and individuals, including gods and goddesses, that helped societies better "understand" the universe.  

Storytelling likely also came into existence as a way of explaining conduct or events that the storyteller hoped would divert attention away from conclusions that would prove deleterious to the storyteller in the event the truth were discovered.  In other words, lying was an early progenitor of storytelling.  Storytelling also evolved from a natural inclination of human beings to seek entertainment.  Plays and fictional stories have been around, as noted, for thousands of years.  Aeschylus was writing plays depicting accounts of historical events around 500 B.C..  Why did he decided to depict events in a theatrical format?  Only Aeschylus can answer that question.  All we know is that individuals were engaging in storytelling activities thousands of years ago.  

If one has to identify the main purpose of storytelling, the inherent need to depict and explain events remains the most important.  Not unlike contemporary conspiracy theories that seek to explain events around the world in a way more palatable to individuals or more consistent with many individuals' predispositions to view skeptically "official" or commonly-accepted explanations, storytelling in earlier eras almost certainly evolved as a way of understanding the unexplainable.  Storytelling also no doubt evolved as a means of ensuring important events and individuals would be remembered.  Tacitus and Herodotus lacked the tools enjoyed by later generations of historians.  Filling in the blanks in what "facts" they were able to attain invariably involved some level of supposition.  The link from that to fabrication, whether intended to entertain with no pretense of accuracy or intended to manipulate public sentiments through subterfuge was short, and enduring.