Also slavery was typically nowhere near as a different sort of brutal in that era. Still brutal and terrible, but not "working people to death and then shipping in more people to work to death" brutal.
Edit: changed my wording because slavery has always been fucking horrible, e.g. eunuchs
Yeah, you got Sundays off and could keep property. Still not a good practice and I don't agree that society wouldn't have been able to function without it (maybe mining)