Are we all selfish inside?

Chapter 9: The Drowned and the Saved
This chapter describes the situation in the concentration camps in terms of relationships between people in the camps. Primo Levi says that most prisoners forget their moralities and only focus on survival, even if it is through deceit and selfishness. Once people are put into conditions as those in Buna, most become stoic and egotistical to concentrate on their own survival; they barely practice altruism. The people described in the chapter who most likely survived the camps, Schepschel, Alfred L., Elias, and Henri, were all self-centered in a way, setting their survival as the priority in life.
After I read the chapter I asked myself, “Can there be a general sharing and loving feeling throughout these camps at all? If there can be, can this help the prisoners survive the camps, rather than self-centered means?”
I then came to a conclusion that it is very unlikely that it happens. People are born with sin, as Christianity tells us, and goodness is what people learn to practice, rather than having it since birth. When circumstances of a person turns ugly to the point of that in the concentration camps, he will likely lose what he has learned throughout life (goodness) and will easily return to practicing what he is born with, which is sin. It will be much harder to keep altruism and love within the people of the camps, since most will focus more on the benefit of themselves rather than that of others. I wonder if Primo Levi, who himself survived the Holocaust, took selfish and deceitful ways to survive.
It is disheartening that this is the reality and nature of men. However, there are very little of genocides like the Holocaust occurring these days, and people can practice good morality more easily. Although the people who survived the Holocaust may be of sinful nature, they ironically helped people of today reduce such genocides by increasing the awareness of the Holocaust.