Ok. Breathe.

What would have happened if the US hadn't entered WWII or hadn't remained in western Europe to stop the Soviets, or hadn't responded to the invasion of South Korea?

Presumably, someone or something besides what we politely call liberal democracy would be running those places, mmm? Probably in the manner in which either Germany or the USSR was run at the time, or in which North Korea is run today?

Perhaps after murdering all the intellectuals and landowners and shop owners, they would have come to some phase of neo-communist authoritarian capitalism like Vietnam or China now, (or if the Nazis had won, maybe their kids would have agitated for free speech and minority rights!) although it's debatable whether a Stalinist or Maoist country could get there without an evil capitalist villain to push it toward perestroika.

I'm not defending America sending troops hither and yon to defend banana companies.

But you say it's breathtakingly entitled to simply state that someone is going to run the world, and I think it's just a plainly obvious fact. By someone, hopefully you understand that I mean a polity and not a person, and ideally a group of nations with a commitment to the rule of law and civil rights. That would be as good as it has ever gotten in the long dark history of the world.