And here we enter the bizarro world of "everybody is the same as everybody else because at some time way back in the seriously distant past (as in, say, maybe a thousand years BCE) some members of their very distant ancestors may have been "slaves" of one sort or another.

Well, dimbo (speaking to the author of that nonsense, not you, Kennardo), assuming you are correct, if memory of that experience of slavery has never been passed on to us and we have zero sense of connection to it, WTF does it matter?

If it wasn't in the recent past (as in post 1500 AD or so) and there's zero left over from our ancestors' experiences in our own, how on the Goddess's green earth can it have even a modicum of impact on us?

If we don't know about it, and nobody else knows about it...WTF are you talking about?