Regarding manners, it really depends on what those manners are.
Chinese medieval society was very orderly and mannered; there were clear standards of behavior (at least for the elites). But the manners in question were conservative and did not encourage innovation, so they did not advance rapidly and ended up far behind Europe despite having a head start. The enforced homogeneity of thought and thus destroyed opportunities to advance or get past their own biases. Read about the Imperial exam system for some reference on how this was achieved, and note that Chinese geography has the most fertile regions highly centralized.
In the west we developed this system of manners based on freedom, where we let people do things we think are wrong, as long as they're not hurting us. This permits intellectual diversity, which means that when the mainstream experts have it wrong, at least someone else can come and knock them over with reality. Rationalism, not authority. Objective evidence, not subjective feelings.
My main worry is that the modern mainstream morality seems to be all about intensive efforts to homogenize thought, opinion, and policy as widely as possible, to exalt collective justice over individual rights, and to privilege subjective "lived experience" over objective evidence. Freedom of conscience and freedom of speech seem to be "out" these days and it's gonna create some real unpleasant results. It already is.
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(Slightly off topic as well:
It's kind of a myth that society didn't move forward through the Middle Ages. While western medieval society remained in the Malthusian trap up until the 1800's, in other ways it did advance continuously over that time.
For example, studies of documents signed reveal that literacy increased continuously from the 1200s all the way until it hit nearly 99% in ~1900.
Similarly, studies of recorded ages reveal that most people didn't know their age in 1200, but more and more people knew it up until the present day. (You can tell this because people who don't know their age tend to round it to end in a 0 or 5, so you can count the over-representation of this in the data, or even by just looking at tombstones).
Something was changing through the whole medieval era.
And there are other markers (e.g. interest rates went down continuously, rationalism advanced, etc etc).)