Humans are extraordinary among animals species in having learned how to cooperate in ten of thousands, millions, and even hundreds of millions. That ability has made us the dominant and most consequential species on the planet. It's not quite unprecedented. Some extremely successful insects have managed the same feat. So, in a way, are the billions and trillions of cells that learned how to live together in a multicellular palnt or animal. Unlike humans, the others have elaborate genetic adaptations making their cooperation possible. Humans, though, are basically the same creatures who lived for millions of years in communities of a few dozen.
How we did that is a major theme of Professor Harari's. His answer is that we did it with the help of "imagined realities," elaborate mythologies structured to dictate, explain, and justify our interactions in society. Such mythologies are encoded in laws, politics, customs, religions, art and ethical ideals. It follows that revolutions, rebellions, and internal struggles - and many external struggles - of civilizations tend to be battles of competing mythologies.
These ideas give us a way to understand not only the religious wars that have convulsed societies for millenia but also many features of the political struggles in our own country. A nearly invariable thread in such struggles is that between hierarchy and egalitarianism. The participants in these struggles are notorious shape changers. Christianity, in it's origins, was radically individualistic for its time, but it was soon co-opted by the Roman Empire and re-created in that's empire's image as the Catholic Church in which form it persists even now. The radically egalitarian Republican Party of Lincoln has now become the aristocratic and racist party of Rand and Nietsche.
It's a familiar tragedy of history that egalitarian movements often, or perhaps usually, wind up replacing one hierarchy with another.