Nice challenge, a thing that is uncaused is ignorance I say.
There is a direct cause for ignorance actually. And at the same time that cause and your ignorance of said cause share the same root, and that's YO MOMMA for giving birth to you (although obviously for other people its their momma, not yours).
Another one is math axioms they can be true and provable
An axiom, postulate, or assumption is a statement that is taken to be true, to serve as a premise or starting point for further reasoning and arguments. The word comes from the Ancient Greek word ἀξίωμα (axíōma), meaning 'that which is thought worthy or fit' or 'that which commends itself as evident'
No, axioms cannot be proven.
And since axioms are "merely" assumptions they are created when people assume them to be true.
Now, those axioms do describe universal truths, but any competent philosopher should know that these truths were of course created by
Chaos at the beginning of time.
Basic logic might indeed be multiversal, but that's obviously unprovable either way.
Oh you want a "thing"? The zone outside of where our universe has expanded to, nothing has reached it to cause anything yet.
Au contraire, the only reason you are able to define it as outside our universe is because the universe was created in the first place.
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But all these things kinda prove my point, as even if you count them ancient people are not going to be big on formal math proofs, and are obviously not going to be observing the space outside the universe either.