perhaps the background (especially in the 1st screenshot) shouldnt have as much contrast to distinguish depth
seconding that. You have your oranges crying for some anti-alias on their edges on 2nd screenshot, too.
I think flies don't fly with their legs extended, too. That would help to hide them for collision guess by the player, too.
Imho, a dark line between the bricks and the spikes on the 1st screenshot would make the scene more comfortable to look at. Possibly it would be good to have more contrast on the candy things. All your colours are very close value-wise.
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^ BW conversion, will help you seeing whether the scene is readable. -- ways to improve readabiliy ^
Now, to be honest, the background tiles could use some work. They're very irregular, with excessive dithering. The skelettons size compared to the fly might break the illusion that we're a fly.
I suggest you post 1:1 assets in additions to mock ups / screen shots, next time. It will make edits & reviews much easier.
