You already got some really good suggestions so I have just a few things to contribute: I think the main problem with the person is not necessarily the light/shadow on him but that the composition of the background leads the viewer's eyes away from him. It is most noticable in the trees directly above him. They create a triangle away from him. The river could be used to lead the eye towards him, but he is too far upstream for it to work properly (since the main focus becomes the rest of the river).
I've not drawn a whole lot of backgrounds though so it might just be me XD