I’m not sure if these would count as lessons, but they would most likely be a lot more closer to themes though. Anyways
1. Having dignity in the fave of inhumane cruelty
2. Struggle to maintain faith in a benevolent god.
3. Death;spiritual, emotional and physical
4. Self preservation vs. family commitment
These are all important themes/lessons because every single person that was dragged into the dehumanization that occurred at the concentration camps, had all expirienced some sort of death whether it be emotional, spiritual and or physical death. Some others had a bery hard time between choosing to only look after themselves and try to survive, or choosing their family by staying with them and protecting them the best they could. But that would also be a great burden on most people because they were desperately trying to survive the horrors of the concentration camps, death camps, etc.