Let's start by what I like: The mechanics, it's definitely an interesting concept, and a creative take on the theme. The game is quite polished in some places, for example the animation of the tutorial guy talking, the fall and get up to look around animation, etc.
As many has mentioned, it's way too hard. I spent more than 15 minutes to get past the tutorial, and was greeted by a harder level, very discouraging honestly.
So here's some suggestion I think could make the game easier:
1. Slower time / weak gravity, to make the platforms fall down slower so player can have time to response and freeze it at the place they want. This will make the it more of a "play with your brain" game instead of "play with your reflex" game. Unless the latter is what you're going for.
2. Preview for what's in the past/future, sometimes I get really lost and forgot which time is the one I want to travel to.
3. Tutorial needs to be improved, possibly split into smaller chunks, don't try to make the player learn everything in a level.
4. A way to schedule the time changes (basically a macro? player can hit a key and it automatically plays J 2 secs later, then L 2 secs later, then K, etc). So the player won't need to control the character movement and time travelling at the same time.
I understand that this is a game jam submission and every thing is done in a limited time frame, so those above are just suggestion instead of criticism. Good job for the amount of work done in 7 days.