My 2c-
It is well understood that China and USA need each other. And that has generally been seen as a desirable situation, if only to prevent the two of us from needlessly going to war over some stupid nonsense.
US has basically outsourced all manufacturing to China, to the point that it would take a decade or more to undo that. We depend on them, they depend on us too.
Most of this is just boilerplate recognition and encouragement of that fact. Stating in a great many words that China wants to continue to be a US ally. But it is also a warning, that China is not a third world nation that the US can boss around as it sees fit. So China is warning us to follow through on our word and generally be honest and do what we say.
The red line things are the real meat of that. This is an instruction / warning to Donald Trump and his incoming team. So the whole message basically says we will work with you and be friends but don't fuck with us on these four issues.
Unfortunately, those are kind of four issues that we really should fuck with them on. USA should not turn a blind eye to human rights violations of any ally, regardless of our level of dependence on them.
And US should absolutely not support China taking over Taiwan. Not just for reasons of principle, but for our own ends- Taiwan produces an awful lot of the world's computer chips. If China gains control of TSMC, that essentially puts them in control of the US economy because if TSMC stops sending us chips, the vast majority of the supply from Qualcomm, AMD, Apple, and others just goes away.
Our strategy so far has been to officially acknowledge the 'One China' policy that includes Taiwan as part of China, while simultaneously taking actions to help Taiwan stay independent. China is calling us out for that here.