Where did the universe come from? Atheistic origin science has no answer.

[snowtracks]

Can't have infinite regression since by definition nothing could begin, nor can have a random generator (no intellect), nor could there be God², God³, etc.

So one option is that the universe, which we can observe and thus know exists, has always existed in some form or other. The other option is that god, whom you claim cannot be observed and therefore cannot be proven to exist, has always existed and created the universe. Seems that the former explanation is simpler and more likely, and does not require us to presume the existence of things we cannot possibly detect.

an unassailable fact : universe is 13 billion years old.

"whom you claim cannot be observed". that part is correct. for instance, an entity standing right in front of you claiming to be God wouldn't be proof.