Nice start and quite fun experience. Im not sure how much energy you are willing to put into this game, so some of these suggestions might sound bit too much if you are just making fun project without plans to release full game.
Things I enjoyed.
- Simple and fun game, suitable for quick and fun mobile gaming.
- Graphics did fits to game theme nicely.
Things that could be improved.
1) Start/Intro scene is bit uncenessary and personally found it annoying after several restarts.
2) Music, I personally had enjoy it more without flute or whatever that high p?tch instrument was, but thats just me.
3) At level 3, just before "goal area" you cant really see where you are jumping and can easily die (unless you paid attention at lower platform), I found this bit too cheap way to make level harder.
4) If time, consider doing "idle animation", it was bit funny to see my character freezing into "movement" position when I was not moving.
Suggestions.
1) Intro/Menu scene.
How about creating "lobby world", so player can move around in small area and enter into "world portals", little bit of interaction is always fun.
You could even place few NPC`s (using same sprite as player, but different color?), pressing "action" button would enable player to talk with NPC`s who could tell game story, praising game creator (credits in funny way) etc.
2) Checkpoints.
Tho its small game, after losing 3 lives whole game restarts which can be frustrating. You could simply restart current level or use "lobby world" suggestion that allowing player to re-enter to the current level (if I was on level 2, I can enter back to level 2 or previous levels).
3) Live drops.
Maybe add random chance of getting "bonus live" from the trees (sometimes live drops, mostly health drops) or other sources, with limitation that player must have less than 3 lives in order to get bonus one.
I will be checking back and test out future updates, of course trying my best to provide feedback and suggestions. Keep up the good work!