The novel is in his name. He possesses great purpose in Fitzgterald's work. Gatsby represents a couple of elements that make him so vital in the narrative. I think that the first one is that he is the embodiment of human freedom and dreams. While the world around him is fairly corrupt, Gatsby is fairly pure in his desires to construct an identity different from his past and in his belief that his dreams can be accomplished. Gatsby believes in the authenticity of his dreams, of his pursuit of Daisy, as well as the idea that human freedom is limitless. I think that the fact that his attempts at his dreams are thwarted are not the result of anything related to Gatsby, as much as the natural limitations of human dreams. I think that this becomes Gatsby's ultimate purpose in the narrative. His presence reminds us of the seductive beauty of dreams. His condition reminds us of the pain intrinsic within them.