This is simple. Nearly all morals come from answering this one question: How would I want to be treated?
This “Golden Rule” is universal enough to be coded by many religions whose writings have been preserved. Some are shown at right. It’s what we expect of our courts and of our people.
Application of the Golden Rule comes with caveats. Namely it assumes the asker is someone who has been basically following their culture’s existing norms. A rapist in prison doesn’t get to invoke the rule.
Things get twisted when out groups are allowed to be disparaged. Blacks were enslaved. Immigrant citizens are deprived of rights, women can’t vote, etc. The holocaust is an extreme example of how horrible we can be when we treat one group as less human than another group just because of who they are rather than what they’ve done.