Not sure if you're looking for critique, and giving critique has sometimes been discouraged on HN, but:
It's pretty good for a week of work. Though there's a difference between being challenging and being annoying. Many of the level design elements could be classified as a "dick move." An example would be not making it clear the goal is to collect all the coins until after the player has bypassed some of them and reached the end.
In general the controls are too sluggish. It's as if triple buffering is enabled, or maybe quad buffering. If you're at a university, you should try to borrow a high speed camera and measure the time difference between when someone presses the spacebar vs when the character starts to jump. I don't know if it's a Chrome thing or what, but I fell off cliffs several times due to the input delay.
The gravity could be better. I'd recommend spending some time with Cave Story to get a feel for how to make gravity really work in the player's favor, rather than against them. In general it's a bad idea to make velocity strictly linear. Some acceleration adds to the experience and precision.
A checkpointing system would be good. I can see how most players will give up after getting mostly to the end and then dying. I think you should just restart players from the last point that they were on the ground without dying, that is, the most recent ledge that they were standing on.
It shows promise. If you're looking for feedback about how to advance as a game developer, one step would be to make sure you're not rewriting your entire game engine from scratch for each game. It's excellent that you're writing your own engines rather than trying to use other people's, so be sure to keep doing that. It's important for gamedevs to have an idea of the underlying principles and limitations, and the best way to do that is to write your own engines. I got the feeling that most of the week was spent on the engine rather than iterating on the gameplay or level design though. Teaming up with an artist or a level designer might be a good match.