Arrow Keys and WAD Press R to reset if you got stuck in any part (resets the current level, not the entire game) Every single level is possible. If you cannot do it, it just has a trick to it, most tricks are dumb and illogical. You can also do what I'd like to call "The Edge Trick", which is basically jumping to the edge of anything and your character will not move from there (better showed in 2nd level)
Inspired by https://scratch.mit.edu/projects/531916886/ Platformer engine made by @warfame_test Music used: https://www.youtube.com/watch?v=gkTb9GP9lVI