What time frame is to be considered for conceptualizing the Harlem Renaissance? Can Harlem Reinaissance be considered something beyond Harlem?
Is Harlem that is as an international phenomenon? What art forms are to be envision as constituting the Harlem Renaissance? What significance or relevance does the Harlem Renaissance have for today's society?
The first answer does a good job of answering most of your questions. The one thing it does not address is the importance of the Harlem Renaissance for today.
I would say that the Harlem Renaissance was part of the first manifestation of what we would call "black nationalism." You can see this in works like Langston Hughes's "The Negro Speaks of Rivers."
This idea has had a great impact on our recent history. The idea was reflected in the Black Power movment of the 1960s and in the rise of the Nation of Islam. Both of these continue of affect society today.
In the present day, we see this idea in the theories of Afrocentric scholars. We also see it in efforts to promote things like Kwanzaa.
The Harlem Renaissance goes beyond the scope of being just localized in Harlem. The Renaissance was a flowering of black art, music, dance, and literature. It led to the fostering of a new black identity; a positive one. White people went to Harlem to listen to the Blues, dance, and be entertained. It allowed for a bridge across the cultures that had never been seen before. It occurred between the 1920's and the 1930's.
Jazz and Blues were the new sounds. Langston Hughes literary works emerged. African Americans had found a collective voice. The era gave way for the next generations to develop additional styles and voice. White artists began to emulate the styles. It became acceptable for a white person to play records by artists like Billie Holiday. The wide spread popularity of the music and forms of art spread across the seas to Europe.