this is very flawed analysis
liberal-like, I might say
No, it’s quite a real phenomenon. It can be analyzed differently by simply saying that if one of your mothers, grandmothers, great-grandmothers . . . got pregnant a month before she actually did - or a month later - the unique DNA associated with you as an individual would not be instanced in the human that you are. It would be someone else, but not you. And not just you, obviously, but the further back you took that, the more it would affect humanity.So if you somehow time-traveled back to before the Civil war and freed the slaves, say, there would indeed be descendants of those slaves - and of everyone else - now just as today but none of us would be those particular people.
So your personal existence, and mine, were contingent on slavery - and everything else that happened 200 years ago - happening exactly as they did. It’s the butterfly effect, actually . . .