Slavery in the American colonies may have started in 1621, but slavery in the new world existed with the first Spanish colony. And the Arabs were enslaving blacks for hundreds of years before 1621, and kept the slave trade going long after slavery ended in the US.
One cute tidbit about the start of slavery in Virginia:
Virginia, Guide to The Old Dominion, WPA Writers' Program, Oxford University Press, NY, 1940, p. 378
"In 1650 there were only 300 negroes in Virginia, about one percent of the population. They weren't slaves any more than the approximately 4,000 white indentured servants working out their loans for passage money to Virginia, and who were granted 50 acres each when freed from their indentures, so they could raise their own tobacco.
Slavery was established in 1654 when Anthony Johnson, Northampton County, convinced the court that he was entitled to the lifetime services of John Casor, a negro. This was the first judicial approval of life servitude, except as punishment for a crime.
But who was Anthony Johnson, winner of this epoch-making decision? Anthony Johnson was a negro himself, one of the original 20 brought to Jamestown (1619) and 'sold' to the colonists. By 1623 he had earned his freedom and by 1651, was prosperous enough to import five 'servants' of his own, for which he received a grant of 250 acres as 'headrights.'
Anthony Johnson ought to be in a 'Book of Firsts.' As the most ambitious of the first 20, he could have been the first negro to set foot on Virginia soil. He was Virginia's first free negro and first to establish a negro community, first negro landowner, first negro slave owner and as the first, white or black, to secure slave status for a servant, he was actually the founder of slavery in Virginia. A remarkable man."
Cleared out the orphanages and poorhouses. Some prisons, too. Progress, though, by 1841 it was illegal to beat your 'employees' in the New World.
Remarkable if true (and I have no reason to doubt the veracity of the above), and shines the light of truth upon a dark subject. Blacks were not the only slaves of the Europeans. The Scots and Irish were slaves of the British as well, especially in the North and Canada. African Blacks, as well, benefited on the supply side of the Atlantic slave trade. The white slave traders HAD to purchase their slaves from black slave merchants in Africa. Slavery is not a black and white issue, it is a human issue.
When the issue of long dead slavery in the USA is replaced with a dialogue about the dynamics of "group", as in country club vs street gang, we all might somewhere. Until then we will fight the Civil War for eternity.