"Not all African Americans are Black and not all Black people are African American." You don't say! First of all, "race" is a social construct and should mean nothing. Although both Elon Musk and Charlize Theron are politically, and, perhaps, legally, African and American, they are not ethnically African-American, as their DNA does not originate in Africa. Idris Elba, as far as I know, does not identify himself as American. Negga does not identify as "American," so no one calls her thus. As for Rihanna, Barbados is in the Americas and was the site of transatlantic slavery. How do you think so many black people got there?

You'll notice that I took the effort to state "descendant of enslaved Africans." McWhorter is both black and African-American, despite which "classification" he prefers. I do appreciate your effort to make your point of view clear, however.