Us vs. Them is "received information." You learn it in school, you get it in the MSM, in movies, rap music, etc. Real people normally try to avoid conflict. Conflict is dangerous, expensive and counter-productive.
The purveyors of Us vs. Them is the big, overreaching hand of Govt. Government thrives on conflict and they go around fomenting it everywhere. Then they resolve it in their own best interest. They have the monopoly on the resolution of conflict even when it involves themselves.
Just as surely as people have negative traits, they have positive tendencies too. People help one another every day, even strangers and without any expectation of reward. What to speak of an emergency where people risk their lives for others, open their homes, their pocketbooks, give comfort and aid - you don't need any laws to force it out of them.
It is misinformation that people are so self centered they have to be forced to contribute to anything, it just isn't so. But yes when everyone is mandated, regulated, prohibited and taxed to within an inch of their lives and you can get sued for trying to help someone, behavior does change.
The natural state is much more faith both in Man and God. That kind of belief changes outcomes, it is innate and spontaneous. But nowadays that gets schooled out of people.
Institutional greed is infinitely worse than individual human greed which is a matter of shame and sorrow. Institutional greed gives cover to the perpetrators who can hide behind unjust laws.