Very creative and unique take on the time-looping mechanics! I really love how the puzzles are designed but feel like the game deserves a bit more polishing in regards of the UX.
At first I thought the past version was replaying whatever I did on the same level before pressing R but figured that it was replaying the action in the previous level after seeing the description. I feel like it would be better to make a note of that in the game to communicate it better. Intuitively I thought I could click on the forward, pause, and backward buttons on the screen by mouse but only learn that I need to press J, K, L in the How to Play screen. The slider is also a bit bugged that I can drag it with my mouse with no effect on the game so that aspect was a bit confusing. And I notice I wasn't able to exit a lot of the menus using ESC which a lot of player would expect.
Given that the levels are tied together, it should also be easier to go back to a previous level and modify your past action as it is now. Perhaps something more diegetic would communicate the fact that going back to a previous level is an expected action of the player instead of using a UI button.
Other than that, this is a very fun game and I like how the puzzles are laid out. Using the rewind and pause mechanics to force a past self to stand in the correct position makes for a nice puzzle!