Hello.
I also tried to level up my unarmed skill but was unable to. Luckily, helper Bunny_Rabbits was on and I was able to ask for help. Bunny_Rabbits told me that McMMO Unarmed was nerfed because of it's OP abilities. The only way to level it up is through credits that you buy or from xp books from crates(or sometimes sold in /ah). As for other skills being useless, everything else works(at least everything I've tried). I have never tried taming, so I don't know if it works.