From what I've read, the Egyptian genetics are still relatively similar to Egyptians from several thousand years ago, due to the relatively small number of Arabs involved in the Arab conquest of Egypt. However, the only kinds of inheritance that I believe are strong are familial or cultural. I don't believe in broad umbrella genetic inheritance claims without any establishable familial connection. Beyond this, I think the idea of geographic artifact ownership claims, based solely on the geographic origin of artifacts, have little to no merit.
Beyond this, I think the idea of geographic artifact ownership claims, based solely on the geographic origin of artifacts, have little to no merit.
That's fine, but the world disagrees with you, by and large.
And it needs to have some way of adjudicating these claims. Granted, fine-grained aspects of "familial" vs. "genetic" inheritance (throwing in migrations and multiple waves of forced assimilation) might muddy the waters a bit.
But the vastly bigger point is -- to a first-order approximation, the criterion of "proximate geographic origin" provides at least some form of an objective basis of ownership, and a reasonably workable and intuitive one at that. Meanwhile, as of the 21st century, the consensus view is that the ownership "claims" of recent colonial powers who extracted these artifacts coercively have no merit or basis whatsoever.
Per what the world at large seems to think about these matters. You can disagree of course, and go stand in front of your local museum and hold up a sign stating so, if you like.
(And nevermind the "solely" part please. Yes, there are corner cases like Anatolia where one group comes in and basically genocides the groups living there, so why should the current population get ownership of everything buried underground? Interesting questions, but again corner cases -- and the current population of Egypt seems to be the very opposite of such a case, for the very reasons you stated).