You're making a lot of weak arguments that aren't based in real historical context.
Xi Jinping absolutely believes in Marxism-Leninism. You could argue there were reformers in past decades that held sway, but he doesn't want to see himself get replaced with a reformer.
There has never been a communist state, when we talk about communists we talk about movements that aspire to communism. Maybe the old CCP operated things more like a command economy, but today's China is more like planned mercantilism, which is a weaker regression from "capitalism" which is itself an inaccurate Marxist caricature of how regulated free markets actually work. The CCP leadership are very firmly Marxist-Leninist.
Industrialization amplified power potentials of trade and production, which did leave Japan and Germany operating below their potentials, but communism threatened them both. Look at the first actions Japan took and who made those decisions and what they were concerned about. Look at the first actions the nazis took in Germany, look at who they allied with Japan against, look at the book Hitler wrote about the threat he saw, look at who he labeled and what he did with them.
Russia is the largest country on Earth, by accident? No, because it expands its empire. China is huge, because it's never expanded its empire, it was just born that way? No, it has taken over adjacent regions and expanded its culture. It even tried to expand into Russia, but Russia threatened to nuke them.
Italian fascists and German nazis were a direct reaction to communists psychological imperialism. Marxist global expansion is itself a contradiction, because they hate imperialism, and yet aim to achieve the same goals. Communist International in the USSR was a prime enemy that Japan and Germany allied against. The US got Stalin to dissolve Comintern to try to deflate German and Japanese motivations, but also because the US was very anti-communist. We just saw Germany and Japan as the more immediate threats to the world.
Russia couldn't have beaten Germany without aid being shipped in from the US constantly.
What the US sees right now is the threat of another world war caused by communism.
Personally, looking at the kind of things you write, I think you should step way back, forget everything you've been taught and instead focus on the fundamentals. Go back into history and just understand the basic behaviors of countries, like they are organisms. How trade, industry, economy, military, geography, psychology, culture, communication, transportation, demographics, power imbalances, etc all contribute to the various behaviors and outcomes. Then you can say, ok, there are all of these details, but how many of the details are just....details and not the trend?
The threat that China poses is unmistakable. They have the warped ideology, societal repression, information control, massive state propaganda, most rapid military build-up in history, they have the largest global network of spies in history, they're threatening almost all of their neighbors (not just Taiwan) and so on. The list just keeps going.
If you think the US should simply sit back and watch it unfold without pushing back at all...yeah, we're not that naive.