There were several literary movements going on during the 1920s. There was the Harlem Renaissance taking place in African American communities with figures like Claude McKay, Zora Neale Hurston, Richard Wright, and many more.

This movement was largely an expression of the African American identity, and with many voices contributing to the expression of this identity there wasn’t a singular picture. Instead, the Harlem Renaissance was a rich and diverse movement that looked at various aspects of African American life through various people. For instance, Zora Neale Hurston’s later work Their Eyes Were Watching God (1937) was critiqued for its use of dialect. While Hurston may have seen this as expressing true voices of the African American community, other figures like Richard Wright saw the dialect as appealing to the white audience. Richard Wright in the New Masses wrote:

Miss Hurston voluntarily continues in her novel the tradition which was forced upon the Negro in the theatre, that is, the minstrel technique that makes the "white folks" laugh. Her characters eat and laugh and cry and work and kill; they swing like a pendulum eternally in that safe and narrow orbit in which America likes to see the Negro live: between laughter and tears.

Other movements were also taking place. In the poetic world, there were figures like Gertrude Stein, Ezra Pound, and William Carlos Williams. A common theme of these writers was the idea of modernity. Questions were asked. Was the city a corrupting agent? Was suburban life too mundane? What were the principles that we should live by? Are there any?

Questions were also asked by other writers as well. Authors like F. Scott Fitzgerald created iconic works like The Great Gatsby. This novel explored the darker reality of the American Dream:

They were careless people, Tom and Daisy—they smashed up things and creatures and then retreated back into their money or their vast carelessness, or whatever it was that kept them together, and let other people clean up the mess they had made.

Tom and Daisy belonged to the group of people classified as old money. These were people who went to the elite schools, inherited their money, and lived in their own separate world. In the novel, these people are shown to be destructive, thoughtless, and living lives of self-gratification.

In all, the 1920s was a time period of vast changes in the United States, and the various writers and artists explored these changes and their implications. In the process of this exploration, the changes were exemplified and reinterpreted over and over.

Look at The Great Gatsby.  You can easily see the new values there.  You can see how obsessed people were with making money.  You can see how the were extremely preoccupied with doing things that would be fun.  They were not very spiritual or "deep."  Instead, they were living on a pretty superificial level.