Slavery has happened since the dawn of man, and continues today. Americas part in this was quite small in relation.
That's one statement that actually requires a lengthy reply, which I am to "out of sorts" to undertake right now. But here's a short reply.
At some time and at some place, every race, religion or ethnic group, were used as slaves.
Conversely, at some time and in some place, every race, religion or ethnic group, were "colonized".
So far as the transatlantic slave trade, one can see that the bulk of the transatlantic trade went to Central and South American, as well as the Caribbean.
So, does that make it right for us? No; but, keep in mind, we were not alone. The slave trade has existed back into the mists of time, and many centuries before
America was discovered, the trade from Africa to Arab countries, dwarfed the entire trade west.
The males transported west were the lucky ones, since most males delivered to Arab countries were made into eunuchs.
Keep in mind, Americans only dealt with slavery for 78 years ! .....Constitution signed 1787...Emancipation Proclamation issued 1865,The rest was with a different boss.