Great job on your first jam! This game has a lot of personality, and there's a lot to do in it, complete with a boss!! I think the sound could have used a bit more development, but for a first submission this is amazing. There's issues with the platforming as mentioned by other comments, but platformers are actually surprisingly difficult to make. Some notes for consideration:
- For an action-focused game, movement is key, and not being able to jump and move is killer. I'm guessing you've got an if/else if block reading your inputs. For left and right, you can store a vector for directional influence, and use two ifs (no else). Apply a positive or negative X unit vector and multiply it by your speed. Similarly, have a separate conditional for jumping.
- Collisions with platform corners, including destructible blocks, are being handled as returning to the ground while some groundings don't get determined, so you can get stuck on the ground until you walk off a ledge to trigger another check on a different ground. I can't offer more specific suggestion without looking at code, but it sounds like you don't do a grounding check on every update. Doing a check every update can easily solve the latter, but the former is harder.
- When a block has something over top of it, perhaps the collider should be considerably smaller, at least enough to be too small for the amount of velocity pushing the player into the block. However, once a block has an exposed top, the collider should be at least as wide as the block, or the player will struggle to land on it.
- When doing the ground check, test to see how much of the player's collider width is actually colliding with the platform and tweak it. Too little, and being near platform corners will let you jump before even landing. Too great, and you won't be able to jump when you're standing only partially on the platform.
- Stacking ropes close to each other allows you to stack upward acceleration, and combined with the limitations of AABB collisions, can make it really easy for you to fling yourself past ceilings and sequence break or even softlock yourself above the level. You should consider keeping track of the sources of "forces" that get applied to the player, so you can prevent this stacking. However, if you wanted to lean into it, you might consider using raycasting for collision instead.
Regardless, good work!