There are many themes in Schindler's list: Virtue, Triumph of the Human Spirit, Redemption, and Denial. Triumph of the Human Spirit is one that is easy to see throughout the movie as people not only survive the horrors that are all around them, but move past what is happening in order to survive. Oskar starts out as a businessman, but is moved by his humanity to save as many as he can. It could even be guessed in the beginning that it was his humanity that overran his greed before he was even aware of it.
One reason that motivated people survive was desire to tell what happened to them. They did what they needed to do through their Human Spirit in order to survive.