I can't believe you didn't use a game engine for this :O
-The gameplay is pretty fun the jumping is a little bit difficult to control at first but once you get used to it you enjoy the game even more I like that the cubes become faster and change position overtime it makes the game more challenging
-The art is simple yet fits the game well
-The UI is really good the shadowing behind the scoreboard ,the player hp and the score gives the UI a lot of depth and make it look better
-The audio is great I like the music one of the best that I have heard in this jam so far
In conclusion I am very very Impressed that you made this game without an engine yet it turned out to be this good, definitely Looking forward for more projects like this bro :D