Very awesome concept, and fun game!
I want to give my thoughts on some of the small issues because I think there is a lot of potential here if some kinks are cleared out.
First of all, there are a few physics bugs, I randomly clip into things a lot. I think most of these issues can be fixed by simply adding some code to push the player or other objects out of terrain/each other when they get inside them which happens fairly frequently. Also, the fact that the item you're holding has collision means a platform can go between the item and the player and you can "hang" off of it which should be easy enough to fix by just moving the collider down a bit.
Besides that though I have some thoughts on each level individually:
Level 1: I believe the intended way to complete this level is to press the button, restart, the spring lands on the platform, and you take the spring. However you can just freeze the spring at the start of the level and bypass that entirely. You can fix this by making it impossible to use your time freeze thing at the start of the level.
Level 2: Not much comment, pretty straightforward, although personally I'd take away the ladder and force the player to jump off the key midair because I think it'd make it a bit more interesting.. Also I would appreciate it if the roof was a bit higher.
Level 3: This level was weird to me at first because of the fact that in this game all buttons are linked apparently and hitting one button causes the others to automatically open, which is never really explained and is very unintuitive. Also, while I understand why objects fall off when you climb ladders (although they should really fall to the side instead of staying on your head), the fact that they randomly come off when you are walking on top of a ladder is just annoying. Also the key ends up behind the door when you try to throw it there.
Level 4: Again a level where I think you're supposed to use the button, freeze it, then restart, but this one like level 1 can be bypassed entirely by just freezing the key and grabbing it, moving it off the conveyer belt, freezing it again, and restarting, so now you have the key off the conveyer belt so you can just freeze the spring and go.
Level 5: I think this level is pretty clever, the intended solution (letting the key go around one loop, then unfreezing the key and freezing the platform at the start of the next) is very cool. However I did it by freezing the key mid fall and waiting 2 loops at which point the platform pushes the key to on top of you and you can just unfreeze it and grab it. Personally I don't really think it makes sense that frozen in time objects can be pushed around or interacted with; the fact that a frozen key doesn't experience gravity but can be moved sideways by a platform is just ???, and same with the fact that for some reason you can press buttons when they are frozen in time. It would make more sense for the platform to get stuck on the frozen key, and only by unfreezing the key can things move it.
Level 6: I didn't really like this level because I feel like it is one that is conceptually simple (throw the bomb through the wall then freeze it so you can pick it up from the other side) but mechanically difficult, while puzzle platformers should really be the opposite. Running out of time when the door is open because you need to pick up the key that's fallen behind the door and is invisible is IMO not the way to make the level hard.
Level 7: Another level with a switch mechanic that can be bypassed by just freezing the bomb on the conveyer belt and grabbing it. But I liked the concept of this one a lot, where you want to put the bomb between the layers then reset and unfreeze it. I did have a weird bug though where the frozen bomb experienced gravity which did make the level easier but I don't think it's intended.
Overall though I really liked the game and the way the two main mechanics (stasis + time rewind) interacted with each other, I think it's awesome and I'd love to see a fully fledged game built around these mechanics. Great work!