The US is far from perfect, but - so far, TBD where we go from here - has had IMHO a net positive influence on keeping democracy around (specifically, I'm thinking of Germany after WW2, Western Europe during the Cold War, Japan and with detours South Korea).
Perhaps you'll point out that the US did this out of pure self-interest and these countries are just vassal states to the US. However, a useful comparison in this context is comparing Western Germany (US) to Eastern Germany (Russia), South Korea (US) to North Korea (China) or, say, Poland (US/EU) to Belarus (Russia) to assess which sphere of influence (and its implications on national self-determination) is preferable.
Going back to democracy, in my view is not the "default state" of human society (the default is probably mob rule like we have in Russia).
> That's the reason why people consider China a "adversary" not morality.
I personally view Russia and China as adversaries because they are a serious threat to democracy worldwide (that I think we agree on?), which I believe is the very thing we're discussing.
So in summary, there are very good reasons to be critical of China (CCP) independent of the current US administrations actions and historical baggage of the US.