Oh, I get it
The reason the Grim Reaper is everywhere is because he is witnessing the deaths of all the leaves. I used to think he would be too busy taking care of all the people who were already dying. Now he's going to have to deal with all the leaves too! The coolest thing is probably how good the artwork is and how well the colors mix together. It's just so awesome to see such lush colors blend together so well. I like how there's little patches of light along the ground.
I guess they are supposed to represent the sunlight going through the trees. It's interesting because if you look closely there actually are some good colors being used. Everything just look so natural, just like what you would see in a professional painting. I can see people like you working on things like that. The tassles of Death's clothing are great too.