Thanks for the feedback. I agree with it. There's basically only three pin features:
1. Attract the shot
2. increase your income (which incentivizes maximizing airtime without getting hearts destroyed)
3. Diamond collision box (rather than circles for all the rest), which didn't add much but I just left it in there.
In the end, I decided that the levels had to be designed as puzzles instead - which you probably can guess from the first two levels, but the third and fourth level were impacted by the bug that placed pins persist through levels. The third level was meant to be fairly easy and give a little taste of being able to experiment with placing many pins, while the fourth level was meant to be much harder and about creating enough income to sustain making pins without losing. With the bug though, you could build up a lot of extra pins in level 3 and then use those to make level 4 much easier.
I agree that there's so much more I could've done. I wanted to explore different levels of bounciness for pins, different "balls"/attacks, different pins with growth stages and elements and many other things. But as this was my first jam and I'm too inexperienced, I didn't have time to explore any of that.