Yes, conflict is inevitable in every society, and much of social science is concerned with what to about this. How does a social group or culture best channel the inevitable aggressions that arise between individuals and groups vying for the same goods or benefits?
Rene Girard, a French philosopher and literary critic, has argued in that all humans suffer from a mimesis of envy, by which he means we inevitably want something as soon as somebody else wants it. For example—and he leans heavily into Shakespeare to support this—once one man desires a woman, another man will want her too: this is precisely because the first man considers her desirable. Girard contends that envy and desire are derivative emotions that arise precisely from living in social groups and observing what other people have or want.
This, he says, will inevitably lead to conflict: in a monogamous society, for example, only one man can "get" the desired woman. He argues that earlier societies dealt with these social tensions by first having human sacrifice in which everyone else in the group could vent their aggressions on one "guilty" member of the group who was blamed for causing the tensions. Later, this turned into animal sacrifice, and in Christianity, this refers to the sacrifice of Jesus.
Girard's is just one theory that explains human social conflict and aggression. There are many other ideas, and humankind continues to work on this problem.