Final answer:
The main idea in this excerpt is that there is still a lot to be written about the African American experience.
Step-by-step explanation:
The main idea in this excerpt from 'The Negro Artist and the Racial Mountain' is that there is still a lot to be written about the African American experience. The author suggests that there is a vast amount of material for African American artists to explore within their own race, and particularly in the relations between Negroes and whites in America. By drawing on their racial individuality, heritage, and humor, African American artists can contribute to literature and the drama with an inexhaustible supply of themes.