It's very good! Congratulations, very good first game. And the sprites are pretty nice too :)
Using rewinding as an attacking mechanic is original! I think it's the first game in this jam that I saw that did this. Really liked it. I was just a bit disappointed that you couldn't rewind the floating platforms and the elevators! But I guess that that has already been done a lot in the jam :)
I think it should have been longer. One or two extra levels would have been enough!
Also, it's not obvious that you have a limit on how many shots you have. I eventually figured out what the number at the top was for, but it would have been better if you had explicitly written that somewhere! Or maybe you did and I missed it: sorry!
I think maybe you could change how you go about the limitation of the number of shots. You could give the player more shots than he needs to complete the level, but congratulate the player on using less than the maximum number of shots: you could even have a "par" number of shots where you get a medal or a star at the end of the level if you use less than a certain amount of shots, for instance. Your last level is actually a perfect example of this! By cleverly using the rewind mechanic (space bar) you can clear the game in only one shot, even though you have three available. That is great! It made me feel that I was better than the average and made me want to keep perfecting my skills. You want your players to feel that!
Overall, good jam entry and excellent first game. :)