BTW, what we think of as "black English" does not come from Africa but rather the British Isles. The use of "be" as a finite verb is one example; "ax" (Chaucerian Middle English) is another.
The early American blacks did not learn English from fellow Africans.
In SE Michigan there is a curious linguism used by blacks and working class whites, it is ‘Alls I’m saying’ for ‘All that I am saying is’. I could never find anyone who could tell me where this speech item came from.