Only thanks to the Librarian unlocking said gift, a gift plenty of people would have in their geneplans that would have been unlocked in time through evolution. Chief just needed it at once.
But Chief is the only human that is able to withstand the composer.
He isn't the only true Reclaimer, plenty of humans are. Librarian's plan wasn't just for Chief.
If this isn't cortana why is she trying to get chief safe so badly?Because he is the original reclaimer, the title given to him by the Librarian in Halo 4 - I think that Master Chief is the only true reclaimer.
However, that is not to say that it something that can just be given to all humans - but how do we we know if Chief still has this power?
He must be of some importance to Cortana (or whatever it is) because what would MC and Blue Team do after 10,000 years (if Cortana succeeded in her plan)?