Heroism

 For almost all of us self preservation and the preservation of our family is firmly rooted in our nature.

Its pretty instinctive and automatic.  Beyond that it isn't so certain.

That is why many if not most people hesitate to jump into a situation that involves a stranger being wronged.  I'm fairly sure that many Germans did not agree when the Nazis started to terrorize local Jewish merchants and eventually rounded them up and marched them away.  They didn't however do anything about it for fear of reprisals and the fact that they didn't feel a connection.

I'm also sure some did, and likely paid a price.  The Nazis weren't kind to objectors, even Aryan ones.

There are stories of heroism where people hid or helped Jews escape.  Still it didn't stop the policy.

We had a similar experience in this country during the years slavery was allowed .From the very beginning some saw the slaves as equal human beings who were being oppressed.  These objections didn't stop it but it did help create some escape routes.  Still it remained the law of the land until the civil war inspired its abolition, more as a punishment to rebellious states then anything else.  

Does doing nothing in the face of injustice make you evil?  It generally makes you average.  Heroes are the ones who  take a risk to help those in trouble.  Yes jumping into a lake to save a strange is heroic, but I suspect the jumper expects to live, if they think at all.  Standing u to oppression is not so straightforward.