Around 2000 BC Yahweh chose one descendant out of all of the race of Adam by which to manifest His Sovereignty and Power. Therefore world history would center around that one family, and they would become many nations, supplanting the old Adamic oikoumene.
While they were permitted to intermarry - under controlled circumstances - with the other Adamic families, nevertheless for purposes of inheritance and tribal identification, the line has always been counted through the males.
This is absolutely clear in Numbers chapter 36:
7 So shall not the inheritance of the children of Israel remove from tribe to tribe: for every one of the children of Israel shall keep himself to the inheritance of the tribe of his fathers. 8 And every daughter, that possesseth an inheritance in any tribe of the children of Israel, shall be wife unto one of the family of the tribe of her father, that the children of Israel may enjoy every man the inheritance of his fathers. 9 Neither shall the inheritance remove from one tribe to another tribe; but every one of the tribes of the children of Israel shall keep himself to his own inheritance.
However Paul did not say "As in Israel all men die, in Christ all men shall be made alive." But rather, he said "As in Adam all men die, in Christ all men shall be made alive."
There certainly were Japhethite males all over Europe when the tribes of scattered Israel began to arrive circa 1500 BC, and they remained afterwards. There also may well have been Hamites, as Egypt as well as the Philistines had contact with Europe all the way to the British isles.
Additionally, there were almost certainly Medes, Persians and Assyrians mixed in with the tribes of the Scythians as they migrated westward. After being established in the west, for centuries German and Scandinavian tribes brought Slavs from the east to use or sell as slaves.
If any of them are among us, we would not be able to tell. Indeed, many Japhethites and Adamites of the other lines are certainly intermingled with us. The scattered Israelites, however, seem to have always risen to dominance. The Parthians over the Persians and Medes, the Romans over the Etruscans, the Spartans struggled, and later the Makdedonians eventually prevailed over the Athenians. The Iberians over the Tartessians.
But what difference does it really make, if they all descended from Adam? Aside from speciation which naturally occurs through generations of isolation, the Israelites were no different than the rest of the Adamic race, and since the settlement of Europe further such speciation is readily evident. But if one is not a bastard, one is an Adamite regardless of what paternal tribe may be one's heritage.
While the children of Israel were assigned a special relationship with Yahweh, and while the other nations of the Adamic race were left to their own devices, in the end they all share in the same ultimate promises, which were made before Abraham and which cannot be broken.