Only edited colours and the rocks a little.

The two problems I have with this are that the grass distracts too much attention and the monster blends into the background too much except for the tongue, which is very bright.

I doubt there is a colour that works both for the monster and the background. I also think that the purple and blue trees should have their colours reversed, but that would give you a problem with the trees behind the ink thing.

By the way, are the things on the ground casting shadows rocks or grass? I assumed rocks, because the shading is rather extreme for grass.

To be honest, it looks entirely black to me even on darker backgrounds.
Using the colour picker on a few images of google most colours I got were desaturated blues, with shadows going into purple to pink. I don't know if that's the influence of the atmosphere or if ravens are really slightly blue.

I'm more concerned(?) about the animation. It's very slow and I don't feel that reversing the animation works where the wings are lowest. I've barely done any research, but from what I've seen the wings generally seem to spend a bit of time decelerating.

As Asti said the door isn't in perspective, and the windowsill isn't either.

The TV-stand and speakers(?) are completely flat, which doesn't help the depth any.

Mostly though, I don't think perspective practice really works at resolutions this small (or pixel art in general).

The d in Windoughs reads like an o.