The game seems to start on the wrong screen, so you cannot see your player, if you keep pressing left and jump it will eventually "fix" itself.
Sound effects could use a bit of work. Some music would have helped. Jumping is a bit stiff while walking is a bit floaty. Lost interest about half way in the 2nd stage, due to too many "walk of the edge of a platform and then jump up to the next one" which is a fun challenge once or twice, but felt like 20 times in a row at some point.