Nice little game. It's fun to play and as you wrote in the description it is still in developement. One thing that annoyed me was that you stopped jumping if you collected something, i don't know if this is a bug or intended but it doesn't feel so good. It might also be nice to have a warning for the thief as it feels a little unfair if you collect something at the edge of the screen and a thief spawns in your face.
But all in all it's a good game and already fun to play:)