finished Superman red son and I have a question

At the end we see this superman really came from the future and not from krypton, right? The earth suffered the same destiny as krypton and had to do the same thing, but in this comic, Superman is technically a human from the future, a future where humans were better than they were, and also is a Luthor, but... Since he is really human, maybe he is immune to green kryptonite, right?