Fun and challenging game! I especially appreciate how there is a lot of enemy variety and how the spear power-up can be used for both attacking and for platforming!
If I had to critique anything, then, as someone else mentioned, the game taking you to the main menu after death should maybe just have taken you to the checkpoint itself. Other than that, I also felt the first boss' normal swipe attack came out too fast. It didn't really give you time to react, so I had to basically go in, hit them once, and assume they were going to do that attack, and get out of the way.
But in general, cool game! I also personally didn't have any issue with the controls, but I was also using a controller. For keyboard controls, if you are unsure, you can maybe look at other popular games and see how they do it. I personally took inspiration from Blasphamous' keyboard control scheme.