It doesn't seem obvious that the fundamental models of reality would just happen to match up with the mathematical constructs that we humans have come up with.
On the flip side, it wouldn't be entirely surprising if mathematical constructs that we have thought of are in fact very good models of fundamental reality. We should remember that, after all, nothing exists outside of fundamental reality, and if certain basic patterns can be encoded such that the encoding is both high-fidelity and simple, that won't be shocking. It might be awe-inspiring, but not really surprising.
>nothing exists outside of fundamental reality
A bold assertion.
This is a deep philosophical debate: Is mathematics invented or discovered?
I think it's a bit less deep than that. It's more, "is the language we use to describe mathematics invented or discovered", which I would put myself (and most people) firmly in the invented camp.