This game is massive for a game jam! So much stuff to explore, and what's crazier is that all of it is quality. Great game feel, charming graphics, solid level design, varied and catchy music tracks. All around really great work!
The "failure is progress" theme here feels a little shaky -- leaving behind a heart when you die is an interesting idea, but I feel like it doesn't really play into how the overall game plays moment-to-moment, and doesn't feel integral to the experience. Most of the time I'd die to spikes and I'd have a heart floating above the spikes that I could only get if I...fell into the spikes again. Maybe having hearts only spawn if you die from enemies, and having a one-use platform spawn above where you died from spikes could help with this more.
I also think having more shortcuts tying back to the start would really help with the pace of the game. Unlocking them with upgrades felt pretty good, but having to kill yourself with the wires felt jarring . There's a lot of backtracking required to redo challenging parts, and I felt it deflated some of the great level design you've come up with.
Overall it was a great entry and one of my favorites out of the jam, and I'll forever be thankful to you for including gamepad support!