Chapter 5 is a key chapter for many reasons, one of which is that it was the start of the original story that Shelly wrote during her trip to Geneva.
Three aspects are worthy of consideration: Shelley's allusions to other works of literature, the gothic references and finally, Victor's response to his creation.
Shelley uses the Bible to contrast God's creation (which was "good") with the creation of Frankenstein, which he feels both excited and appalled by. This comparison allows us to see a wider theme of the dangers of playing God and how risky it can be to push the boundaries of science. Later on, Shelley alludes to "The Rime of the Ancient Mariner" to underscore Victor's feeling of loneliness and also his haunted state, feeling persecuted and chased by his creation.
Shelley builds in many gothic qualities into this chapter, including grotesque details of the monster's appearance. The monster is described as "beautiful" yet repulsive, with his "yellow skin" and "lustrous black, flowing" hair. Other gothic qualities include the eldritch, scary environment of Victor's lab at 1 am and his feeling of psychic communication - his paranoia that he is being persecuted. Throughout this chapter an impending sense of doom and fear is created, which will come to bear on the rest of the story.
Lastly, Victor's reaction to his creation is to run away. When the monster tries to communicate to his "maker", Victor flees in fear. The creature only wants acceptance from Victor, but when Victor flees the creature is abandoned to a confusing, lonely world where he will be alienated. This reaction is contrasted sharply with the friendship and support that Clerval offers to Frankenstein. Some critics argue that this is the true tragedy of this novel - by his rejection of his creature Victor evaded his responsibilities and highlighted his own moral failure of not loving his creation.