> That's fine, but the world disagrees with you, by and large.

I honestly don't like the way I ended that last sentence. If I could re-write it I'd replace "merit" with "basis in cultural lineage". I would agree that most people in the world don't default to feeling this way, but I also don't think most people have a well thought out idea of why they disagree. If it is considered that the current geographic ownership claims are retroactive ownership claims based solely on the current owners of the geography, for items that existed on the land long before the current legal nations came into existence, the claims make much less sense.

> the criterion of "proximate geographic origin" provides at least some form of an objective basis of ownership

This is part of the reason why I don't like how I used "merit", as it could get confused with legal merit, which wasn't really my intended meaning. However, the problem with this argument is that many of the cultural objects that were collected in years past were collected prior to the modern nations existing in those places. Due to this, this argument really would have little legal merit for virtually all the countries where artifacts have been collected, as those countries did not exist when the British collected the artifacts, and their current claims are a retroactive idea of ownership over what was collected before the current nation came into existence.

>the consensus view is that the ownership "claims" of recent colonial powers who extracted these artifacts coercively have no merit or basis whatsoever

There may be a opinion in the popular consciousness about this general topic, but there can't be a legal consensus, as every claim has to be evaluated individually. Without documentation on the origin and the original owners of the artifacts, and documentation establishing that said artifacts were retrieved illegally, it is impossible to establish legally that the current owners do not actually have ownership over the artifacts.

>the current population of Egypt seems to be the very opposite of such a case, for the very reasons you stated

This is very much not what I stated. The civilization that created the ancient Egyptian artifacts is completely distinct from the current culture. Besides having genetic similarities, which all humans do to some extent, modern Egyptians have near zero cultural lineage tracing to the ancient Egyptian civilization.