Okay, there are several things. I'll check each one out so that other people have a better experience. But no big changes, I intend to work on a fresh project :D
Please notice that the overall experience of the game is great. I don't want to seem mean I was just trying to provide a bug report. The game is fun and enjoyable. If only I think I would've add more checkpoints, but maybe it's just be not being used to hard plataformers