The general purpose for the development of Greek myths was to explain things about the world: how it was created, why there was thunder, sea storms, or any number of natural calamities in the environment. The Greek myths were also written to help people to know the right way to live their lives.
Love was a common theme in Greek mythology. Some deeply devoted couples received wonderful gifts from the gods in the face of the extraordinary love they shared. Cupid and Psyche accidentally fall in love, while Venus tried to get rid of Psyche, jealous of her beauty. Cupid's love for Psyche is unquestionable, but Psyche's sisters put doubt in her mind. For doubting Cupid, Cupid and Psyche are separated, and Psyche almost dies, but Cupid saves her.
The story of Eros and Psyche revolves around the issue of trust.
Stories such as these showed the love was a valuable part of life, and those who treasured it, reaped great rewards.
Prometheus was said to be not only responsible for shaping the form of human beings, but he became an advocate for them as well. He tricked Zeus into accepting a "poorer" portion of meat so that humans could have more. Zeus was angry at being tricked, so he took fire away from humans. Prometheus stole fire and returned it to people:
Prometheus promptly went to Olympus, stole a spark of fire from Hephaestus, and carried it back to humans.
(He was punished by Zeus for thousands of years, but Hercules finally freed him.)
Greek mythology has also affected language. Many words we use come from mythology. One example is narcissism, which means "excessive vanity." Discord means having a dispute or disagreement. Both words come from Greek myths.
Greek mythology has had an enormous effect on cultures all over the world for countless years.