Great question! I think when we consider this novel one theme that we cannot ignore is how children process and understand concepts beyond their comprehension. It is particularly interesting that, thanks to Byron, Kenny imagines the Wool Pooh as a physical representation of death, that he has to fight firstly when he nearly drowns in the water by Collier's Landing and secondly when he tries to pull a girl out of the church after it has been bombed. Chapter 15 of the novel shows us a young, sensitive male trying to come to terms with all that he has experienced and trying to make sense of all that he has witnessed. It is only after he is able to talk with Byron that he comes to understand and process some of what has happened to him.
Another key theme of this work is family relationships. Throughout the novel, Byron and Kenny have a kind of love-hate relationship that oscillates between Byron bullying Kenny and Byron protecting and being kind to him. The author paints a realistic family with a series of relationships that are trying to cope with various conflicts, chiefly the struggle of the parents to bring up Byron to be a well-adjusted young man with strong values.