I know a lot of people have said this, but this is a really interesting surprise to see a level editor in a game jam. I really liked the idea of being able to export and import levels, but I couldn't seem to get it to work, even on the downloaded version. Maybe you did not have time to implement the export functionality? I'd also consider just using right click for erase, it's much easier than going back up to the top to select the eraser. As far as a few bugs, I noticed when you push space while playing, it spawns the scene an additional time, but the original is still playing behind it. Also the enemies aren't affected by gravity, if you put them in the air they just hang out haha!
It's super cool that you were able to make this work in such a short time, impressive, nice work!