Hi I found your game via reddit and I did not play it for to long, I just had a quick look. Here is some feedback:
Make your "cutscene" at the beginning and if there are any more skipable.
Give the player an indicator that he is in a cutscene at the beginning I thought my controls where not working.
Reduce the delay before the characters talk in the cutscene and redude the total time of the cutscene if possible.
If you are making cutscenes like this try to make it feel more natural. All your characters are talking to themselves, it feels weird.
The controls are to stiff and there is no difference between being in the air and on the ground.
Make your tutorial text to show the complete thing on enter and then skip on a second enter, also think about reducing the time to show the text. Its fine if the text is there to fast we need to press enter anyway to continue.
Give the player more time to jump even after they technically did leave the platform they are standing on. I had fallen to my death more than once, although I could have sworn I did press the jump button at the right time.
If you are dying because you are falling into the "void" you are falling to long, make the respawn happen quicker.
I know you used kenneys assets, but try to add some effects (e.g.: Particle effects) or something, for a better feeling.
I hope this will help you. I guess you programmed everything yourself which I think is quite an acomplishment. I would suggest to use a finished engine, it will make your life easier, but if you prefer to do everything yourself that is fine as well.
Good luck to you.