I think the balance is ok'ish, for me at least. For instance the second type of foe (the mummy bear-like things) has too many HP to focus on when you only deal 20 damage. However, that drove me to avoiding them and focusing on the knife guys first to build my experience. The point being, it forces you to make choices.
What could make it more rewarding to actually kill them in the beginning is if stronger enemies reward you with more experience.