The concept was intriguing with this game, though I didn't really feel it's presence in the actual game. Which was unfortunate, ignoring the concept though it is a interesting base for a platformer though personally I did feel like the movement and some specifics were a little bit off, to the point of being annoying to lose to a bit.
Specifically for me it was the fact that, and this may have just been visual, but when I would jump the jump was powerful enough to basically always hit the roof, which lead to a lot of bump the head situations where I would get "bounced" down into a trap of some sort. Which, makes sense, in certain situations where the roof is clearly low enough for that, unfortunately it happened quite a lot, outside of those situations for me at least. Which made it a little harder since I always had to keep that in mind.
Otherwise though the movement itself felt alright and relatively responsive. Unfortunately though I do feel as though the hitbox on the character was, off, in some way. I'm not sure if it was just too big which lead to causing extra deaths just a couple times, or if it was the visuals squishing enough to not fit it etc.
One final thing would be the fact that the rewind mechanic is visually cool, but unfortunately I feel like the fact that there is no limit to it combined with how it shows you your entire time before dying, causes a lot of times where you're stuck just waiting to get back to the beginning rather than actually restarting after death etc.. I do feel like if the goal was some sort of rage game etc. or some punishment in that way, it could be worth doing like that.
The problem in my opinion though is when there is absolutely no limit on how long the rewind id is. Which leads to an exponential punishment for failure where you're sitting there and watching how long you played through the level. maybe some sort of cap, or some skip button etc. I do feel a minimum before skipping would be nice, once again though if the goal is a rage game, that way you get the point across that someone died in a really whatever way,. Obviously depending on how they died.
Overall though this is a decent set of mechanics with what I would be interested to see as a more integrated concept for the gameplay and or story. Plus there is a relatively nice twist right at the end of the game.