Overall, nice work!
I don't really know is it just me or one time glitch, but I felt like the hit box is bugged or maybe the hit box was actually bigger than the image? I dunno.
Next is melee combat being so unforgiving, the range felt too short and if I tried to get closer, the boss will move a bit and touch me so yeah, I don't know how to use melee, maybe you can learn one or two from megaman zero, they also had a melee attack and touch damage but doable.
The bosses are pretty challenging especially when their HP run low and goes rampage, I died like a lot when it's happening as Healing Cooldown is quite long or maybe it was set that way for the difficulty or game balance or something.
Some of bosses attack are nonsense like a Tiger setting up a bear trap where it would make more sense if it was done by a gorilla but I'm fine with that, as for everything else are probably alright.
That's all I guess? Well, if I said something wrong or missed something, let me know.