Oh, thanks for the feedback! This was actually the first game I made, so I knew going into the jam that it wasn't going to end up being very polished. That being said, there is a little bit I'd like to clarify in regards to what you brought up:
1) I didn't have time to fit the story into the main game loop, so I just stuck some text into the end of the tutorial that briefly mentions the story. I definitely would have added some more stuff at the beginning of the actual game if I had the time to do so. As for the attack damage, the bat you start with deals 1 damage by default, and I made the basic enemies have 1 HP (the flying and spiked enemies have more HP and damage than the basic one)
2) I originally had the player need to re-press the jump button after jumping, but because of how I wanted to handle short-hops, it ended up not doing that, and like mentioned earlier with the story, I didn't really have time to fix it (as it is, I barely submitted the game in time)
As for the other stuff, again it just boils down to not having enough time; I would've added more background objects and stuff like that and I probably would've found a different program for making sounds (I used sfxr, which makes more retro-style sounds) and I did notice the glitchy pixels on the slopes, but I wasn't sure how to fix it at the time and didn't want to worry about it too much since I needed to make the full game playable first ^-^;
And I never actually had the game crash while testing it (though to be fair, I didn't test much at the end because I had no time) so I'm not sure what could be causing that. Sorry!
Anyways, thanks for all the feedback! If I ever go back and update this game for something outside of the game jam, I'll definitely fix up the things you mentioned!