It appears that the present-day form of African American English is not the inheritance of the period of slavery, but the creation of the second half of the 20th century.
“A few years ago no hotel or restaurant in Boston refused Negro guests; now several hotels, restaurants, and especially confectionary stores, will not serve Negroes, even the best of them.”
“That's what's so great about my job. I get paid to do what got me in trouble in grade school space out and play with my imaginary friends. In terms of Isaac, when the time's right.”