Hi!
you're right, the difficulty spikes a lot with level 2 ranged enemies. However, they can be one shot once they stop attacking (I think even without upgrades) if you just keep colliding against them.
On the upgrades, we know there's a bug regarding saving when you die: you must wait a little before dying again because the skills apply over time (we didn't find other solution, its a jam game after all)
On rotating to hit the enemy, you're supposed to aim to them with the mouse and hit them with your body. Having to rotate a lot to hit them with the spikes is unintended, so we should've balanced that better.
Sorry for your experience! We will keep in mind all this feedback if we launch a post-jam version :). I appreciate that you post your opinion.
Cya!