Hey there and welcome!
You have a fun concept going there, and I think that I can see where you are headed with the idea. Most of my thoughts are based around creating a bit more immersion in the piece, much like what your story told.
To drive home your story I think it would be helpful to show the edge of the grave that the viewer is climbing out of, it will extend your image downward a bit. But it will also provide more foreground elements and really help define your scale. Pay close attention to the camera perspective, it will get a bit confusing.
You might want to exaggerate the perspective angle of the body a bit more, but that's mostly aesthetic.
Consider going harder on the light bleed from the sun around the character, since he is back lit it would be very intense. And you can use that bleed to really push the thickness of objects too. And the hat will provide a great light frame to keep that wonderful glow working on his face just like you have it, which was a great idea.
Maybe frame the image a bit more with the tree branches, really think about the angle you are looking up at and how much of the underside you would see of them.
Its looking very good, keep at it!