So it must just be an immutable feature of human societies bigger than a clan. Learn to live with it, stop obsessing? Your death is another immutable feature. Why are you not obsessing about that one? How about `family`?
`Class struggle` is pattern you can look for and discover anywhere. The same is also true for `love`, `heroism`, `greatness`, `evil`, `corruption`, `technology`, `achievement`.........
`Class struggle` is a poor view of history. Reality is so much richer.