Reddit mentions of Black Africans in Renaissance Europe

Blacks in Europe were free before and after the start of the slave trade and it is only the boom of the slave trade which enslaved people with black skin into slavery forever. As the slave trade was in it zenith, there is documentation of free slaves arriving from the Americas to settle in European cities and took up trades. Some became musicians, writers, painters, scholars.

While some worked in houses and the like, they weren't slaves in the way one would think of slaves in the Americas. They were servants, seen as people, although inferior/subservient, and not slaves/farm equipment/beasts.

If you want to read more on this, you can start with this book and work your way from there.

Or you can go here, I just found this and am editing in the link:
http://afroeurope.blogspot.com/2010/08/history-of-black-people-in-europe.html