The 'Gift' of men and the Athrabeth

[Telchar]

I dont have much to say right now, but last night reading in SILM nor the Nth time, I stumpled on this:

In those days, moreover, though the Valar knew indeed of the coming of Men that were to be, the Elves as yet knew naught of it; for Manwë had not revealed it to them. Bat Melkor spoke to them in secret of Mortal Men, seeing how the silence of the Valar might be twisted to evil. Little he knew yet concerning Men, for engrossed with his own thought in the Music he had paid small heed to the Third Theme of Ilúvatar; but now the whisper went among the Elves that Manwë held them captive, so that Men might come and supplant them in the kingdoms of Middle-earth, for the Valar saw that they might more easily sway this short-lived and weaker race, defrauding the Elves of the inheritance of Ilúvatar.

Try to put this in regard to what we know of Mannish tradition concerning immortality of men. Comments, anyone?

Cheers T