So, I would suggest picking almost another character to be the PC avatar, but I get that it's recognizable.
I think even a very basic song in background, along with a "jump" noise would push it little further, but it seems to function in terms of jumping and spikes.
You work on some level walls as you can fall out of either end, there is no need to make a collectible unless it effect the game in some way, but the coins did collect well.
I hope to see more from you, and thank you for making this.

Really bad. No story, no animation. The background image even has a watermark on it, meaning you stole it from the internet. Sucks!