I appreciate the uniqueness of the mechanics, but there are a few fundamental things I think could be tweaked (this is just my opinion, and honestly I think this mechanic has a lot of potential):
Perhaps this is just because a lot of people have played grappling hook games in the past, but there are expectations for how to handle movement, in particular swinging. I feel like there is no control over the ability to swing in this. There is no way to rock back and forth and create momentum, at least from what I can tell. My brain kept telling me that what I'm "supposed" to do in this game is: swing to move the level, timing the world rotation until i can make the correct jump to either land safely or grapple again. Somewhere there is a disconnect however.
What I end up doing, is firing the hook waiting for the swinging to stop, then seeing if i can jump from my grapple position so i can fire and pray that the rotation doesn't land me into the spikes. I almost feel like this game would be better without spikes.
You have done a really great job in subverting the expectations for character movement (which in and of itself is hard to do successfully so major kudos for attempting this within the constraints of a game jam), and that should be the challenge more than the level itself (if that makes sense).
Heavily hazard driven levels tend to benefit more from having a precise character controller that gives the player as many tools, especially familiar tools that are easy to pick up, as needed with the challenge being the level and mastery of the simple controls. This is probably why some people enjoy Kaizo Mario games. Everybody understands the rules, and the level is subverting the expectations. Even though it is "frustrating" you understand that it is a process of mastery over the simple character controller (and in the most diabolical ones, brute trial and error over things like..troll invisible blocks).
Bennet Foddy style games (Pogostuck, Sexy Hiking, etc) , you subvert the expectations of the control of the character, making it complex or foreign, but keep the levels fairly simple. Nothing kills the player and forces a reset typically in those games, though your progress may be impeded by a simple challenge proven exceedingly difficult by the mechanics of your characters movement.
Perhaps I'm sounding overly critical of a game jam game, but I really like the concept, the polish, and even the overall game feel. I would say, remove the spikes from the tutorial level. Throw that out again to players and see what there reactions are. I feel you are onto something great, it just needs some tweaking that game jam time limits wont allow. I'd definitely keep experimenting with this idea, I'd love to see more done with this!
Again, I hope this didn't come off as too critical, my goal is to encourage you to keep iterating on this and have it live up to the potential I feel many here see in it! :)