What a pleasant experience. I had a great time with this, and you should be proud of yourself. Im going to be very critical in this comment, but while reading it *please* remember that i had a good time playing your game.
There were aspects of the game here that were ametaurish, which, i suppose is natural if you're newer to game development. The character, for example, would get stuck in midair if you moved into an object while falling, and got really kind of annoying before i adjusted. This is actually a really easy fix (at least in unity, idk godot) for your next game. Upside-down echoes didnt appear to be upside down, which like, mechanically was unimportant but kinda brought me out of the game a little bit.
I think you missed a lot of the potential of your core mechanic. The mechanic really lends itself to puzzles, and i was hoping the game might go in that direction, but instead you seemed more interested in platforming. Which is fine! i just feel like the time rewind mechanic was just like,,, door levers but you have to go back to the start each time you hit one.
Sound and ambiance was lovely. not much to say on that. Art was also pretty good, though sometimes (especially in the first room) the platforms were a bit hard to see beacuse of the lighting)
let me reiterate: you should be proud of yourself. well done.