Thus, black slavery was instituted by a black colonist.
That's an interesting story but unfortunately, or fortunately depending on your point of view, it isn't true. The first known case of court ordered indenture for life, aka slavery, occurred some time before that. And the owner was white.
"Whereas Hugh Gwyn hath . . . brought back from Maryland three servants formerly run away . . . the court doth . . . order [that] the first serve out their times with their master according to their indentures, . . . and that [the] third being a negro named John Punch shall serve his said master or his assigns for the time of his natural life here or elsewhere." - A Virginia Court Decision (1640) from Virginia Magazine of History and Biography (January 1898), vol. 5, no. 3, p. 236.