Fun fact, the 2 longest periods of peace in history are called the Pax Romana and Pax Mongolica. The Mongolians and the Romans are known for fighting wars, lots and lots of wars. The only prolonged periods of peace in history are when one country or empire gets much stronger than the rest.
Another fun fact, the lowest per capita worldwide war deaths in a specific year in world history occurred in 2019.
And finally, when the US goes isolationist, the rest of you animals start killing each other instantly. So keep it up if you want a lot more "history" to happen in your lifetime.
Both the Pax Romana and Pax Mongolica saw their share of violence - plausibly comparable to 19th century Europe, or the Han and Tang dynasties, which which were not unipolar. We just don’t have good numbers for any of these cases. The long-history basis of your argument is flimsy at best.
The US itself only began resuming mass offensives with the decline of the USSR. But a world collapsing into unipolarity should lead to less conflict according to your view, as there would be less incentive for inter-state violence. The other pole was undergoing collapse, and the US sent soldiers, and continued to do so for decades.
But strictly speaking 2019 is part of a longer term downtrend in violence between nations after World War 2. That’s a trend that preceded American hegemony - a hegemony which is frankly a shadow of its former self. The real risk today isn’t multipolarity, it’s that the US is denial of multipolarity. Vietnam, Iraq, Afghanistan, Ukraine, Israel. The US just doesn’t have the money to hemorrhage out to military disasters any more. It’s a house of cards growing taller and taller. What has no limit is the foolish arrogance of our leaders. The way to stop war is rarely escalation (anathema to the defense lobby).
And we are all human beings, US and non-US alike, not animals. It’s the capacity for compassion that makes us human, not the ability to kill.
Another fun fact, the lowest per capita worldwide war deaths in a specific year in world history occurred in 2019.
And finally, when the US goes isolationist, the rest of you animals start killing each other instantly. So keep it up if you want a lot more "history" to happen in your lifetime.