Where is a question that can only be asked if there is a coordinate system.
What do I mean by this?
Okay, so you know the room God is sitting in? That room is also God. It's just a part of him that he turned into a room. Okay, but what about the thing outside of God? The thing outside of God is just God himself too. Because there is nothing outside of God. God already includes that everything outside and inside. Because there really is no outside and inside. To have an outside or inside, God have to split himself into two part, an outside part, and an inside part. At that point, the outside part and the inside part are still just parts of God. Also, a coordinate system doesn't even exist until God split himself into some kind of plane, and then separate that plane from the other unlimited part of himself. This is why they say God is truly unlimited, in every way.
But what about the guy that created God? Technically doesn't exist. However, God can split himself into some guy and pretend to create himself, if that's what he wants. Doesn't matter. In the end, it's all still just God himself. Just another part of God that he himself split into. All him. There is nothing else. Just God.
The universe? Just a part of God that he himself splits into, then afterward, he lay down some rules and laws for that part of himself to obey. He call these rules the Laws of Physics. Earth? Formed from the universe through the Laws of Physics that God set. Human? Evolved from evolution, which are rules naturally occurring in a natural environment in a universe bounds by the rules God had set.
Note that it is also meaningless to ask when God was created or when God first appeared, since time is an artificial restriction God created to bound our universe and to force our universe to play by. God is not bound by this rule. Which is why they say God is eternal. Because time is only an artificial restriction that God set upon our universe.
No, it's not.
> so it doesn't leave loose ends out there like, "Yeah, but where did the giant turtle come from?"
How is “Yeah, but where did God come from?” not a loose ends almost exactly like that?
> It's monotheistic, so complications about where the many gods come from, what rules they have to follow, and how they die are moot.
It has a single creator (like many polytheistic creation myths), and multiple supernatural entities raising the same type of questions (even if you literally interpret the serpent as just a really smart snake with an unexplained defiant streak, by the end of Gen 3 you’ve got the cherub with the flaming sword.) That the supernatural entities besides the creator in the Judeo-Christian tradition are called something other than gods doesn't actually eliminate any of the issues they raise.