especially seeing a lot of us, including me arent at that math level of group theory and stuff.
If you're in high school and are doing OK in math, you're probably at the level to understand the basics of group theory. Other than basic combinations and permutations, you'll probably never learn group theory at school, and unless you major in pure mathematics at university you won't get to it there either.
When people talk about cube theory, I don't think they necessarily mean learning the mathematical field of group theory. I think they mean more along the lines of understanding a bunch of cube specific concepts that don't need any math to understand at all.
Commutators and conjugates are basically essential if you want to be good at FMC and BLD. They can also be used to solve any type of permutation puzzle without ever having to look up algs, which is pretty cool.
This video gives a pretty thorough introduction for cubing.
Jaap's Puzzle Page has a lot of cube theory. If you're interested in group theory and how it applies to cubes, then
start with this, then you can go into
this more detailed article on group theory, which also explains how each section applies to Rubik's cube in particular. You may get a little lost, but read a bit, leave it for a while and then come back to it a few weeks later. It doesn't take any particular level of math, but it is fairly heavy reading and will probably take a bit of thinking to understand.
Do I think any of this helps with speedsolving? Not really. But cubing is my hobby, and I'd rather actually understand the cube rather than just apply a bunch of memorised solutions.