The high jump is kind of weird to do. You can just hold down the crouch key for around a second, and then jump. You hold W as you jump in the air to dash into enemies. (Hold Right Click > Jump > while in the air, press W and space to dash)
I hope that helps (in the full game, Wayside Satellite, which I'm working on, the controls have been made smoother, so I'm taking your feedback)! I believe in you!