You may balk at this as being ultimately futile but our entire existence is built on trying to break apart and simplify the world we exist in, starting with the first cut between self/inside and other/outside (i.e. "this is me" vs "this is where I am" - a distinction that becomes immensely relevant after the moment of birth). Language itself only functions because we can create categories it can operate on - regardless of whether those categories consistenly map to reality itself.
The cause of the universe must itself be uncaused, or else it is only an intermediate cause that must itself refer ultimately to an uncaused cause. An infinite regress is impossible with respect to existence. Unlike causes per accidens which can in principle be infinite in length, a cause `per se` cannot; without a terminus, there would be nowhere from which the latter causes would derive their force, so to speak, like an arm pushing a stick that is pushing a rock that is pushing a leaf. Meaning, the cause is not some distant one in time, but one always acting; otherwise, everything would vanish. The only cause that could have this property is self-subsisting being.
From there, you can know quite a bit about what else must be true of self-subsisting being.
So the cause or dare I say reason for the universe being the way it is will depend on its cause.
"The universe" cannot be that cause, as the universe and everything in it is contingent.
But the universe is contingent. It isn't necessary. It is one big chain of dependence.