If the dunedain found Meneltarma
 

If the dunedain in the third age before Angmar's assault on Arnor, found the island of Meneltarma, would they have settled down on it? In a way, returned to their ancestral homeland?

First, the Meneltarma remaining above water after the Downfall was only a belief among the Dúnedain, never proven.

Second, the peak itself was described as being very steep. The apex was only accessible via a winding road that almost certainly was destroyed.

At the top, it was said to have been "somewhat flattened and depressed, and could contain a great multitude" (UT A Description of Númenor), but that doesn't translate to being livable. They would have needed suitable land for farming, and mountain peaks don't typically fit that bill.

But...but...but...the Eagles could fly them on and off. At least until the invention of the helicopter.