I was not originally going to post here. However, engineer_comp_geek, I think your post needs real revision. It is not all wrong, but much of it is just misleading enough to really confuse.
Now, before I go into all this, nothing I say here will excuse any historical injustice. I can describe a great many of them all day long. Human history is filled with people doing all kinds of nasty things to one another. These are simply all the facts I can communicate in a short space.
Europeans did not create the slave trade; they discovered it, and then expanded it. Slavery was a not-trivial enterprise in parts of western Africa for centuries. As Europeans ventured down the coasts in search of India, they found existing markets in various kingdoms. This was not a great surprise to them; both Spain and Portugal knew of the trans-Saharan slave trade through North African kingdoms.
Actually venturing in to capture African peoples as slaves probably happened some times, but it would have been very rare compared to purchasing them from the major slave markets, such as Luanda. Europeans rarely ventured beyond the slave ports themselves, although as time went on some colonies were established. These were tiny enclaves compared to the large colonial empires built in the 19th century, however.
The slave-trade did two things, neither of which were intended by Europeans. First, they brought power to those who possessed the markets. And active port meant wealth, and wealth meant goods - including those with military value such as guns. And all that together meant power. For those who did not have access to such markets, it meant becoming a huge target. Now, trade links did form, so that some groups far inland became very powerful, but on the whole the slave trade radically increased conflict. It also transformed many who might not have otherwise been attacked into victims, either as groups or as individuals. Women might have been left alone previously (although war is a cruel business and people can be pretty bad regardless) but now they were represented profits, too. Captured soldiers might have been allowed to go free in prior times, or perhaps could have joined the kingdom that captured them; but once sold that was no longer possible. The net result was that those willing to lead slave-taking wars and raids saw their power grow, while those who would not or could not might face ruin and collapse.
On the flip side, the consequences for the slaves that lived to reach the new World could be horrendous. Death rates among slaves in some colonies reach frankly impossible levels - impossible without constant cargoes of new slaves to replace them. Conditions in Saint-Domingue, which became modern Haiti, was killing off something like 10,000 slaves annually for an entire century. That’s a million souls, and from records a huge proportion were dying extremely young compared to the free population, either of disease or overwork or starvation (because some plantations effectively didn’t bother to feed their slaves) or accidents.
*As a side note, I’m sure that Saint Dominic, who famously lived an austere and monastic existence, really approved of naming a slave-holding hell growing luxuries after him.
Not every place in the New World was like that, of course. In some places, slaves formed a new peasant class, oppressed somewhat worse than those in Europe but at least able to live full lives. A fair number were granted liberty and joined the free population. In some colonies enslaved women often married their masters and raised families like any other mother would. And in much of the New World slavery never put down roots at all, such as Mexico or Canada or eastern South America.
Of those who came to the New World, about half went to Brazil, and a bit less than half went to the Caribbean. Somewhere in the ballpark of half a million went to the English colonies and a similar number to northern South America. This is somewhat misleading, however, because some areas, such as what would become the United States, purchased few slaves from Africa ports, but rather brought them over from Spanish or Dutch Caribbean colonies. In total, something like twelve million souls entered the hellish confines of the slave ships. Probably one-sixth, on average, died in the crossing.
Now, to clarify just how awful this was, imagine being rounded up by people from the next major city, manacled in a ship with almost no light or even the ability to use the restroom for three months. Every sixth man or woman with you dies and their corpses are hurled overboard. Then you’re dragged off naked and sold in a strange land and the even the fellow slaves around you may not speak the same language. If you are lucky, you may now work on somebody else’s farm for the rest of your life, perhaps forty years. If not, you may now work on somebody else’s farm for the rest of your life which will be about one single year before your abused body can take no more.
[I can also describe slavery in the early British colonies as well, but that’s something of a side note, so I will leave it there.]