Hey great start. I think an important thing to remember for a jam is that people will be trying your game for the first time whereas you have had the whole time playing it and you know what is coming. A safe first area lets the player get a handle on the keys and what the movement feels like. If you had a restart then the player can iterate more quickly rather than needing to refresh the page. I am pointing this out because you have put a lot of work into the later parts but players can bounce off quickly if it starts off too hard.