Nailed the theme.
Some effects for picking up the apples would be nice. And as a major improvement, if you want to continue the work on this game after the jam: Give the player something to buy from his money ;)
The artstyle is pretty solid. Just two tips to improve the art with nearly no work. Delete the bottom black line of your trees, so it looks more like they come out of the ground. Flip some of the trees or if you make several sprites, just delete or add one or too branches. 30min of work and a bunch of tree variants ;)