I haven't reached it but I am very certain that the level cap is 99. At that level, the MC has 250 HP (I think) and 100 MP.
The MC can also hit an average of 200+ points while wielding the normal ax (I'm not talking about the two-handed ax).
As for your proclamation that combat is too easy at level 21...
GOOD!
I spent the first 10+ hours of this game grinding to level 22 so that I wouldn't have to fear encounters with bears when going about my in-game business.
I don't want to grind another 10+ hours because some people feel the game is now "far too easy" for them now.
You want a challenge, fight bears buck naked.

Just don't give
Tinkerer any ideas about making the mobs harder.
Most of us are playing this game for the porn, not the combat challenge.