We cannot really say objectively that the Harlem Renaissance “helped” American culture. That is because there is no such thing as a better culture or a worse culture when it comes to things like music, literature, and art. All of those things are good if a culture thinks they are but there is no way to say which culture is better.
Instead, perhaps it makes more sense to say that the Harlem Renaissance helped to make American culture a little bit more diverse. It did this by bringing more African American voices into the mainstream of American society. The Harlem Renaissance did this in a number of ways. It brought African American authors such as Langston Hughes to national prominence. However, the main impact on American culture was probably the creation of jazz and its introduction to white American society. By exposing white American society to jazz, the Harlem Renaissance put a uniquely African American art form at the center of white society for the first time. It made an African American musical style one of the most popular in American culture. This was clearly a major step towards diversifying American culture.