The Greek philosopher, Epicurus, was convinced that life exists on other planets, so the concept was not unknown in ancient times, and all three Abrahamic religions could, if necessary, produce some sort of evidence to claim they already knew it existed.
Actually, if life does exist on other planets, I've often wondered if Moses, Jesus, Mohammed, et al, have to go through an action replay of their lives on earth - just to spread the message, you know. If that is, indeed, the case, there’s no doubt poor old Jesus draws the short straw every time. :o/