Green surfaces would hurt the overall esthetic a lot. yes, it would provide contrast, but imo its not needed. solid black tiles are good enough a contrast in this case.
The atmosphere is magical, albeit a bit monochromatic. I'd love to see a few slight hue variations in the near foreground plant life, like petals, fireflies or something along those lines.
When it comes to rendering, theres a lot of single pixel lines in your leafes. in still images it works sorta fine, but as soon as you start animating this, especially in parallax, it might jerk around a lot. make sure to test this early before realizing to late that it might not work out for you.
Another slight crit would be that the character doesnt look based in its environment. since it looks so monocromatic, his brown and white doesnt work so well imo. the red is a nice contrast however, and works decent as a style choice.