WIY so stupid he think “yo momma” jokes just from African American culture. The jokes are basically puns that have been recast as insults and were part of English-speaking culture for more than 100 years. I remember versions of the jokes that preceded the “yo momma” versions that were the same jokes but with slightly different set-ups. And most of the jokes are no more insulting than the stories of the Wise Men of Chelm.
As for borrowing from African American culture, popular music for the last 150 years has been heavily influenced by African American culture, and in turn, popular music has heavily influenced so-called “Jewish music,” by which I mean that awful stuff recorded by guys names smellky or ichy or dorky and sold in the bookstores that sell siddurs and Talmuds