'God' is a placeholder for an absence of understanding – a default response to unanswered questions.

Well-put.

It has always been so. There used to be a god for everything we didn't understand (Poseidon, Bacchus, Ares, etc). The Hebrew people actually acknowledged those gods (e.g. "thou shalt have no gods [plural] before me"), but yahweh ruled them all. Not sure precisely when, but they ended up moving to yahweh as a one-stop shop. Then, as we learned more, there was less attributed to a deity. Except for reality-denying fundies, it's mostly just what occurred before the first Planck time, and life/consciousness. We have verified models for pretty much everything else.

A lot of people are uncomfortable with "I don't know". Which is sad, because that spurs investigation. If you say "god did it", then you're sorta done. No investigation needed. But, so far, every time that was given as an answer, someone else dug into it and figured out "no, it's really like this". Every time.