Dear god, what have I done? This is such a long post. I'm sorry in advance - for what it's worth, I do like the game!
It's a very good start. Others have already voiced some of my concerns with the current state of the controls and platforming (coyote time, midair actions, etc). I do have too many a couple of things to add, however:
The most critical bug I encountered was during the boss fights; twice I encountered an issue where my character stopped responding to left/right directional inputs. I could still jump and attack, but I couldn't move. This always happened right after getting hit, and forced me to return to the menu and reload, so I assume whatever function prevents movement during the hit animation isn't properly returning control in some edge case (read: button-mashing). I played with a controller.
I don't know if it's a bug, but even after making a successful parry, there's a pretty significant delay before I can parry again. This is a problem when attempting to parry a hail of multiple projectiles close together, in which case there's a good chance a second projectile close to the first may either hit the player or need avoided before it can be parried, and this doesn't feel as satisfying as it should. If the delay is intentional, there's no visual or auditory indication of when the parry is available again, and the timing isn't related to the animation, so it feels arbitrary.
This is a big accessibility thing: text and controls need to be highly readable, at least optionally. Right now, it's just somewhat readable, with some letters barely so and some only resembling what they're supposed to be, at least in the pause menu. Controls also don't have color to them, which can help sometimes (the Y prompt on interactables could stand to be yellow, as it always has been on classic XBOX controllers). Mark Brown of Game Maker's Toolkit fame has a lot to say on this subject.
In checking on this, I found another bug: The spawning of at least some hazards is not paused by the pause menu. Pausing in the lava zone where fireballs shoot up will hide the existing fireballs, but more new ones will spawn and fly up after a second or two. If the player happens to have paused midair, these new fireballs can actually hit them, cause damage, and send them into the stratosphere! Who ever heard of dying in the pause menu, right?
For the controls, using Y to advance dialog boxes and select options doesn't feel right. The conventional scheme is A to advance and B to go back, so this will work against many players' muscle memory. Remappable controls would make this a non-issue, and also make the game more accessible for, I dunno, folks who play with one hand. For reasons.
There is at least one instance where selecting between options in the dialogue only allows the down input on the d-pad and not the up input.
Lastly, I would say the small tentacle animation in the first zone just isn't very dynamic. If it's a placeholder, it's perfectly fine, but if not, I'll go into detail on what I mean. The character's face barely changes throughout, and there's very little movement overall. The best animation exaggerates movement to sell what's happening, but this feels like almost nothing is happening. The whole tentacle ought to be pumping at the end, sort of like the classic "bulging garden hose" in cartoons, not just a tiny little bit next to what's inserted. There's some odd stretching with the ankle that's on the ground - just let it lift up! Make it look like the tentacle is completely holding her up, and the leg not being directly grabbed is just along for the ride, scrambling around for footing and sometimes lifting off the ground entirely.
I think that's about all I have to say on the game itself. Last thing I'll comment on is the itch integration, which is pretty bad. Is there some issue with using butler? I happen to agree with its documentation that says installers are the worst. I just want to hit Launch in the itch app and see the game come up, not click through an installer like it's 2005. Does GameMaker do some weird nonsense that requires its installer be used for the game to work properly? I understand if that's the case, though it would seem like a risk for the longevity of the end product.
I hope this all doesn't come across as negative; I know how critical early feedback is in game dev, and I want this game to succeed!