And many didn't, and none produced the kind of mass industrialized war capable of dozens of millions of casualties. But yes their ruling classes still waged war for the same reason as our ruling classes do. So it isn't a problem of human nature, but a problem with having a ruling class.
But never before have the underclass actually held the tools and means of production, and been as directly opposed in every rational interest, as the exploiting and exploiter classes produced by capitalist social and economic relations. Furthermore, the working classes are broadly opposed to war, broadly in support of rational, secular government, human rights, and freedom of association. But because the education and dissemination of info to the masses is overseen by the ruling minority, people lack the ability to name the problems which we face.
So our social forces that produce war, are imperialism, which is a historic stage of capitalism. So we can concretely identify specific tendencies in a society built by people, name them, and subsequently resist them; rather blaming all problems of society on "human nature". We can be much more accurate and specific than that. And the moment we are, we have an imperative to do something. Which is why fatalism is so convenient for people who fear freedom.
That's how people who consider themselves rational and scientific end up falling for apocalypse myths; with facts underwriting eschatology. I think there would be less conflict and difficulty in the world if people were 50% less gullible.