Even if what you are saying is true, it still does not take into account how they were treated when they were stacked one upon another inside a confined area with urine and feces draining down to the floor, or being crowded and herded up on slave-ships where slaves. It was simply too brutal of a system. As there were too many slaves being brought into the Carribean/North America, they were just treated as expendable and the average life-span of a slave working in the Caribbean, for example, was normally not longer than 5 years, assuming they survived the Atlantic passage and even getting on the boat. Slavery, as it is known in Africa is different from the racialized and brutal slavery for life and generations practiced in America. There is no historical precedent, even in the Bible, or anywhere, for that type of chattel slavery. If the Africans knew that was really what was being perpetuated then maybe they would not have sold their enslaved tribesman, so some deception was employed.