If it were in your power to do so, would you go back to the early 1600s and (somehow) eliminate the institution of slavery across the entire western hemishpere?
And you think slavery is only a black and western hemisphere thing?
How about ask the question: Would you (being black) go back in time and not go into the bush, catch your enemies tribes peoples and sell them to the whites.
And if anyone says that they would not try and stop it as per your question.... is crazy.
Don't really see what selling your enemies has to do with it. That's how slavery worked from time immemorial. It's western slavery that changed things by making your race a reason. In the past you could become a slave by war, criminality or debt. To put the notion of race into the reasons why other Africans would capture and sell to whites, is to inject an ethic that wasn't part of the equation at the time, but a peculiarity of American slavery.