If an alien race were to present themselves on earth and show us that they were here a couple of million years and that they set the seeds for life on our planet, would they be our Gods?
Ummm .... err ... did they make their own seeds from materials they made themselves out of nothing whilst no such thing as a universe had existed ? Might be a factor in deciding whether they are Gods.
There are of course ideas about that aliens had a hand in major changes on earth and that our myths, religion included, are what remains of the history relating to that, much altered and limited by the ignorance, etc. of our forebears - Chinese whispers style.
I guess it depends on your definition of a god. If an alien race were advanced enough to sow us like seeds, they could have created souls as well and perhaps those that make the grade will get transplanted to a bigger allotment after death.
I'm currently grinning ear to ear at the thought of Naomi on her knees at the bottom of the garden worshipping the rhubarb.