Revelation says specifically 12.000 from each tribe . And no one has commented on the Great Crowd , who are in front of the Throne
jh : going back to the exodus/ passover theme of the OP. Originally it was the firstborn of each tribe leaving Egypt, the passed over ones, that were supposed to t take the lead, direct worship in the young nation, --- until Moses, Levi usurped that by institutionalizing a clergy type monopoly arrangement. ( writing the narrative too).
Rev. 7 brings it back to the original, the 12 000 are the token firstborn of each tribe, that will be priest, leaders.
the non- anointed leftover after that sealing , the ordinary joes, and josephines could well be that great crowd. after all there is nothing wrong with having some take charge, like the 144 ks/
revelation is ambiguous though, the New Jerusalem ( the 144 000 ) is said to come down from heaven, with open pearly gates, named after the 12 tribes. Supporting the idea, that the great crowd, the 12 tribes will stream into it to get at the water.
One way or another. all Israelites ate the bread, (later drank the wine) the lamb. blood on the doors, not just the [future] kings or priests. ALL. families. not just the firstborn.
not one text is offered to justify that big black hole.
the exclusion from partaking of most, for whom Jesus died.