This was my first game jam too, I just saw the announcement, realized I was free this weekend and attempted to make something for it. The best part was probably coming up with ideas for it, but when it came to cramming trying to implement those ideas that's where I kinda faltered.
Here's the game I made btw. Wish I was able to get it to run in-browser but I ran out of time: https://quid314.itch.io/number-line-runner