I tried to exit the level but it would not let me.

You have much yet to learn.Make the scrolling happen when the character is midscreen.Take some drawing lessons and improve your art .Record some sounds and put them in the game.
Next time,draw a few more enemies,variety adds to the fun.Make an enemy kill sound,a player death sound,jump sounds,moving sounds,a game ain't fun without music!Add background music,level complete music.Keep learning and you will improve your work.

it isn't the worst thing ever however their are a lot of problems: screen scrolling as you reach the end, animation/character design, jumping through walls,length etc.

The controls are almost game breakingly stiff, the screen should scroll with the player instead of having the player to reach to the end of it, because then you can see what is ahead of you.If this game is a demo, then please take this criticism into consideration, I hate to see this kind of stuff be posted on Newgrounds in this day age age.