Why do you send the player all the way back to the beginning ;) I got so far...

So I really like the sprite you have for the main character. As a bit of feedback you should look into a few things about platformers and how to make the controls feel tight. Specifically coyote time. Some pretty good videos such as "5 reasons your indie platformer sucks" and which lays out some pretty cool concepts to add polish to your jump as with platformers that is the players main form of interaction. Biggest piece of advice is keep going!