The African American community has set themselves apart with their own definition of music and culture. People have labeled their music and associated it with violence and people have started associating with it and trying to live as those portrayed in the media.
Entire books have been devoted to this subject and it's beyond the scope of a limited Ask answer to characterize. Stereotyping of blacks in the media date back to vaudeville, which shaped the sort of stereotype that later developed in radio, film and TV. The first African American to make a tidy sum of money playing an idiot for film was Stepin Fetchit. His predecessor was a bit wiser, using double-entendre in the know-nothing stereotype and that would be Bert Williams, first black to perform in the Ziegfeld Follies (stage only).
Fast forward to Jack Benny's servant, Rochester, who embodied his own variety of wisdom mixed with his idiot stereotype. Flip Wilson took the idiot humorist a step further, using skits to make social and political commentary in the midst of a variety show.
Your study of this topic only begins here. There is far too much more to cover.