There's a big difference between symmetric and public key cryptography when it comes to this sort of explainability.

Public key cryptography like RSA, Elliptic Curves and Lattices have elegant mathematical theories behind them. Learning those will teach you much about why things are the way they are and how the security boils down to well known hard problems.

Symmetric key cryptography like SHA2, SHA3 and AES don't have nearly as much theory behind them. It's a bit of a dark art where functions are designed to thwart known attacks. There is no foundation like a proof that shows breaking SHA2 is equivalent to prime factorization or anything like that.

This doesn't necessarily have to be the case, there is research in 'provable secure hash functions', but these tend to perform worse, and we value performance a lot in symmetric crypto.