The essential error is the conflation of degree of advancement and metaphysical nature.

If ancient ones were visited by aliens, then these aliens were liars for they claimed the mantle of angels and spoke of the Throne of The Almighty One God.

I find it even less satisfying than plugging knowledge gaps with "god" stuffing. Unexplained phenomenon from the past? Aliens did it, and you know, they work in mysterious ways.

At least with a god, you get a complete origin(1). With aliens, you just punt the "how did life originate?" question to a galaxy far, far away.

Its hella good fun for a few episodes of Stargate, but somewhat lacking as a cosmology.

(1) As long as you are prepared to deal with the "where/how did your god originate?" part.

It's modern sun god mysticism loosely veiled in science (go astronauts!) in order to get around that pesky thing called evolution. Evolution is universally accepted by science and if you dig deep you realize everything on Earth is connected in all kinds of ways via multiple evolutionary paths.

What's more probable is that IF any ET exist they live in a galaxy far far away...too far to ever travel to ours.