it's very possible that others from other planets already mixed and mingled with Urff People
i can't see the technology that popped up in the last century as being all man made -
maybe they placed a few humans in an environment where they could thrive and live to their fullest potential - and aided them with what they would need to be fully human and think at faster speeds
maybe God came down from his high level of existence and assisted man in growing to heights that would make him unrecognizable to the common man.
maybe this God is waiting until the ones he took up are ready/ripe enough to repeat the process without him - and scoop a few more up at a set time.