[Belegorn]

The Dúnedain were slow to reproduce and perhaps events on the island stayed the birth of children to some extent as Elves are known to do when they are engaged in conflict. Meneldil could certainly have been the youngest survivor of Númenor because Isildur too was born in Númenor though an older man. A great portion of the Dúnedain were probably born in Númenor that were still around 122-124 years later till Isildur's death. I just think that statement means he was the youngest of the survivors of Númenor.

I think it is a good point that the view of the South toward the North may have extended almost from the beginning of the 3rd Age. In Gondor the Dúnedain did look askance at what they saw as a "small thing" in Arthedain. I mentioned Eärnil was one of the few who was of a different view "I do not foget the loyalty of Arnor, no deny our kinship, nor wish that the realms of Elendil should be estranged." [Gondor and the Heirs of Anárion] As great a captain as he was Eärnil could not even bring himself to bring aid to Arthedain for almost 30 years when it collapsed.