Answer:
I don't really know the history to why Americans started bringing over Africans to be slaves, but is probably was just because Africa at the time was very advanced compared to the rest of the world, so it would be very easy to capture Africans and send them over to America to be slaves. Once that happened, people didn't think it was wrong to own a slave, and then started think of the slaves as inferior to them. Thus started racism. In short, I believe (as far as American history goes) that it was slavery that lead to racism. Just remember that the African ancestors sold their kinfolk to the white man. The white man did not sail to Africa and loot people. They were sold by their own kind.