Very cool art and design!
Honest and constructive criticism:
The game loop of collecting items and then gaining more playable characters is a really good idea! However I felt the implementation was a bit stiff. The small view angle and walking around the map almost blindley wasn't very fun. After dying I didn't want to repeat that step of collecting items again for battle... it's a kind of frustrating and I would suggest to change up this mechanic(maybe allow the player to try the battle again with the progress they managed to achieve last time).
The game crashed once upon changing the location of my butterfly :(
Overall a great idea, great art you did by yourself! good job!