First of all, thanks for the kind words, this is the first game jam I took part on and I also started the development kinda late, since I had no idea of what to do for the half of the week, so it's really cool to see people playing my game and leaving positive comments.
I absolutely agree with everything you said. The problem with the music loop (and the fact that it gets ultra repetitive after just two stages) was a thing that I realized only the day after submissions ended, since I left to do the music at the end of the development, I was tired and just wanted to end it as quick as possible to go to bed.
About allowing the player to type "left" instead of "l", that is a thing that I didn't accounted for, but I can clearly see this as an improvement, for sure. And also, in retrospect, how did I not think about adding a grid? Well, thank you for the amazing feedback!