Flobadob. I know what you mean. If aliens showed up with proof that they set our existence in motion then those who believe in the God of Abraham would be in a bit of a hole, to put it mildly. Their religions would be proven wrong and would be no more. However, the appearance of extraterrestrials would not automatically preclude the possible existence of a genuine almighty creator of the universe, although it would have to be something other than, and rather different to, the nasty chap most believers around here choose to worship.
Actually your alien scenario is perfectly feasible - in fact I think that’s where the stories of all gods, including the Abrahamic god originated - but since we now understand that the wonders of science are not magic, I doubt we would consider extraterrestrials to be gods these days. However, with human beings being what they are, some may well make up fanciful stories about the real creator and take to worshipping him - even though, since he has no history, no one can possibly tell them he professes to love them, or that he will send them to hell for their misdemeanours. Some people just need religion.
Naomi sits back and waits for the howls of derision. :o)