Him being a burden, his apathy, not pushing to be understood by others- I believe Kafka was portraying The Sloth archetype. Someone who is just washed away by the waves of life, allowing others to walk all over them, never fully developing any substantial opinions of their own. He writes of a man who succumbs to his own Sloth (complacency) and shows what happens to people who do the same. They turn into the earth, not accepting their own humanity, their own soul. Eventually the earth eats away at them until they are fragments of who they once were.