Hey, thank you very much for playing! I can't update the game while people are still voting for the jam, but I will add the ability to jump with W as soon as I can. As for the game loading, for some reason the game takes some good seconds to load for the first time, but somehow this only happens in the browser version of the game.
Answering your question: I'm a solo dev. The music and sound are not mine but the rest I did on my own. I specialized in computer science and programming and make pixel art as a small hobby. I saved time to polish the game by making it as simple and unrisky as I could (a platformer).