Family separation is likely an important part. Many families were torn apart during the Holocaust, and the boy in the story might have experienced this, which added to his pain and struggle. Also, the experience of facing the inhumane treatment of the Nazis, like forced labor and living in overcrowded and unhygienic camps, is a key aspect of the story.
The key elements could also include the boy's interactions with other survivors. How they supported each other, shared resources, and perhaps even formed a sense of community within the camps. His journey of losing his innocence in the face of such brutality and his possible attempts to resist, whether it was mentally or through small acts of defiance, are also crucial elements in understanding this story.
Survival would be a key element. The boy had to find ways to stay alive in the extremely harsh conditions of the Holocaust.