I agree about the characters, they were actually the first thing I drew for the game and I feel like I got much better at art towards the end. I also had a lot of time to polish the background and tiles but the characters had to stay the same after I created their animations.
It's a good point about the jump, I think increasing the player's gravity a bit more could probably really help, I didn't think to do that.
Thank you for the feedback, I'm really happy you liked the game!