GJDS, as Casper and I have tried (in vain) to explain to you, the studies that look for the most recent common ancestor (MRCA) of humans (and postulates one within the last few thousand years) does not (and I repeat, does not) show that humans uniquely descend from that MRCA.
As a way of understanding this: my cousins and I share a MRCA in either of our common grandparents. But we, as a group, do not uniquely descend from them - we have many other ancestors. If we were to examine the genetic variation of me and my cousins, we would see the evidence that we descend from many ancestors, not merely our two MRCAs (our common grandparents). So too with humans as a whole. We may well have a MRCA in the last few thousand years - though those studies are models that, in my opinion, do not adequately address the fact that humans were widely dispersed into places like South America, Australia, and Micronesia several thousand years ago, but I digress.
I’m not meaning this rudely, but you simply do not understand those studies. Your other claims also reveal that you don’t have a working knowledge of how evolution studies, or population genetics, works. I’m not sure I can do better (on short notice) than what I’ve already written (at length) here at BioLogos, so I’ll refer you to that. Perhaps one of our more knowledgable commentators will have more time available to try and help you - if you are interested in being helped, that is.