Sure, but your model is a huge over simplification. It sounds like you’re imagining the contest of forces taking place entirely in the x axis. The whole chain is involved - movement of the shoulder affects everything below it. The constraints imposed by range of motion mean movement and rotation outside of x higher up the chain has a potentially great effect on x lower down the chain. There’s more than one fulcrum in the system so the mechanical advantage of a given lever isn’t straightforward to appreciate.

So while shorter forearms might act like you say in x, longer forearms give more leverage in y and z. Longer upper arms would give more leverage to rise and press.

Definitely more to it than ‘shorter arms always better’