Where the Númenóreans destined to perish?

[The Lady of Ithilien]

No. I'm asking about human nature. You have the Númenóreans who had basically everything that a civilization of Men ever had, and still they ended up being destroyed. I wonder if that is how Tolkien view humans, I wonder if we are destined for failure in his eyes.

But they weren't destroyed: that's the whole point about the escape of Elendil and a few others of the faithful from the ruin of Numenor.

And about Aragorn, eventually. Perhaps JRRT viewed humans as a battleground in which there are many casualties but always resurging hope due to the human spirit that will not give up -- "the old that is good does not perish, deep roots are not reached by the frost" (a paraphrase, as the books aren't handy).

It takes some time and reflection to connect Bilbo's poem for Aragorn with The Akallabeth, but the connection, I believe, is there, signified perhaps by how Aragorn was known in Rivendell: Dunadan, or Numenorean. (And in the external story, a rather neat linkage between The Akallabeth, The Hobbit, and The Lord of the Rings.)

Interestingly, Ar-Pharazon and those Numenoreans who landed on Aman with him weren't destroyed, either, though their fate was far worse than that of the Faithful who escaped the Downfall but had to labor hard in Middle-earth. The rebellious Numenoreans who had broken the ban were buried in the Caves of the Forgotten, to stay there until the Last Battle: they got a taste of immortality, that is, and I bet they would really understand the meaning of the gift of Iluvatar by the time they would be released. So, they didn't fail, either: just got taught a very hard lesson.