Gatsby is "great" because his story represents more than himself.
There are several different ways to examine the importance of Fitzgerald's title. When developing potential titles, Fitzgerald wanted to convey how the story he presented was meant to represent more. Titles such as "Among the Ash Heaps and Millionaires" and "Under the Red, White, and Blue" suggest that Fitzgerald saw something universal in Gatsby's story. He saw Gatsby as "great" and wide in terms of his reach into human hearts.
Gatsby's dreaming can be universally appreciated. Fitzgerald creates Gatsby's dreams with boundless hope. There is an optimism in Gatsby's pursuits which is "great." For example, when Nick says that one cannot go back into the past and cannot recreate that which was, Gatsby's response is "great": "Of course you can, old sport." Gatsby is unwilling to be stopped by time or space. He simply wills his dream into reality. Such self- driven redemption is seen in Nick's description of Gatsby's dreams: “The truth was that Gatsby of West Egg, Long Island, sprang from his Platonic conception of himself.” The language here confirms Gatsby as "great." Gatsby viewed his dreams as "truth."
The ability to believe one's dreams are infallible truth can be evidence of Gatsby's tragic nature. It can be seen as being doomed to fail. However, this is what makes Gatsby great. Gatsby is great precisely because of this unwillingness to accept failure. Fitzgerald makes Gatsby "great" in his title because of how it applies to human nature. Gatsby's dreamer status is our own. Gatsby might have failed; however, his ability to dream is embodied in millions of people.
Fitzgerald knew this. He saw the Roaring '20s as a time where the ability to dream did not listen to reason. Like Gatsby, he saw people who were willing to believe that "the rock of the world was founded securely on a fairy's wing.” This might have been faulty logic, but it was human understanding. Fitzgerald saw his protagonist as "great" because he spoke for so many human beings. This is one of the primary reasons why the work endures today, almost 90 years after publication:
Gatsby’s magic emanates not only from its powerhouse poetic style — in which ordinary American language becomes unearthly — but from the authority with which it nails who we want to be as Americans. Not who we are; who we want to be.
Fitzgerald's title works because it represents what it means to dream. The dreams of being more than what reality dictates defines Gatsby. It also defines us. It is the reason why Gatsby is great. It is the reason why that there will continue to be dreamers like Gatsby, people whose dreams will "beat on, boats against the current."