Our relationship with China is complex and nuanced..... and the Trump cult is not. Which is why they use this meme. It makes a nice soundbite, and it requires a nuanced discussion to debunk that soundbite. They need soundbites like 'Hillary sold our Uranium to the Russians', or 'no collusion'. They are not capable of discussing in depth what those things mean. They just post them, and when you disagree, they say 'fuck you faggot'. This is the level of discourse at JPP. It is what it is.
As for your first point, IMHO, the Democratic party (I hate the term 'leftist') has always been the party of the working class. They have sadly fallen victim to big money as well, but at their heart, Democrats are the party of Roosevelt and Johnson. They are a party that at their core believes that a rising tide lifts all boats. That is a sharp contrast to the core economic value of Republicans, which is 'trust the rich to keep the economy afloat'. We have plenty of evidence to determine which works best, but Republicans are incredibly skilled at getting people to vote against their economic interest by providing them with boogeymen. Mostly through racist dog whistles.