Ok , first of all, your comment got posted twice somehow. So I deleted one of them.
It's sad that you wasn't able to finish it. I now that it's a long tutorial, but you will get the point after you finish it. You were already quite close. There are only two enemy levels before the tutorial is over. Sad that you stopped there.
Now to your feedback.
This was the first game I really used a system that talks to the player. I agree that I might overdid it with some of the dialogues, but it was somehow fun to write them.
The game only told you not to complain about the controls if you are using the keyboard, so your feedback is ok. We (or mostly I because I was the programmer) took inspiration from Hollow Knight and that game also has this all or nothing control type, which i personally like a lot. For me it makes controlling the character perfect. I hate games where the player has a weird or long acceleration or deceleration phase, because it makes the controls feel floaty or like pulling your character with a spring. But yeah, controls in such type of games are always a point of discussion and you can't make it fit for everybody. Especially not in a game jam :D
I agree with the invulnerability time. Unfortunately the web and windows build have the problem that the flashing of the player is not shown correctly. The white flash is shown as invisible, which I couldn't fix in time... But yeah, increasing the invulnerability time would help, but this could also lead to the player exploiting it. Tricky stuff to tweak.
You have to run through the door to activate the checkpoint. I wanted to add a sound effect, but forgot it due to all the other stuff having priority.
For the combat, I had an instant attack response before, but changed it after tweaking the attacks. I can agree that it's a little tricky to perform the right attack, but there was again not enough time to design the enemy levels. The movement levels before are all carefully designed.
Regarding the theme. I agree that we will not get full points on that, but we had this nice 2D platformer in mind and the story which unravels itself after the tutorial (which you didn't reach). So we went with a game that we enjoyed making instead of some weird game. Similar to your game :D
For the graphics, this should answer our graphics designer. But the particle system and trail were made by me and yeah... Time issue. I had really nice particle systems in mind. The jump effect was done very quick before the submission and I'm not happy too.