I don't think the current Egyptian civilization existed when those artifacts were created either.
The modern Italy is quite different from the Ancient Roman civilization. Modern China is quiet different from ancient China. Ancient Babylonia is quiet different from modern Iraq. What's your point? Are you suggesting that we all go off on looting parties and take what we want because the underlying civilization is no more?
Those that have inherited the land, inherit the artifacts from that land. Ancient Roman artifacts, on Italian soil belong to the Italian people. Ancient Roman artifacts on Spanish soil belong to the Spanish, etc.
The Rosetta Stone was found in the Nile Delta by the French. And the Nile is in what country today?... No hurry .. take your time ... Begins with "E" ...