Which is what I find strange about the Century of Humiliation. Why is China losing a minor war that killed a couple thousand Chinese soldiers a great humiliation while getting outright conquered at least twice (once by the Mongols and once by the Manchu) isn't?
Tens of millions of Chinese died during the Manchu invasion of China. The Qing forced every Han Chinese male to shave their forehead and wear a queue on the threat of death, but that's apparently not humiliating.
Following the Opium Wars and other conflicts in the 19th century China actually lost territory and sovereignty in part of its own territory in the heart of China. Suddenly areas of Beijing are controlled by Europeans, and so are many Treaty Ports" along the coast.
When the Mongols and Manchu conquered the Chinese "Crown" it was more of a change of dynasty and they they effectively became Chinese. Mongolia was part of the Chinese empire until its fall in 1912, for instance.
Mongol or Manchu brings more lands to them, and eventually they (Han Chinese) assimilate the invaders. The English took land and the Chinese haven't able to reverence yet. Not to mention this event happened more recently.
I think this is the main thing. While the Mongols and the Manchus defeated China militarily, they were assimilated culturally within a few generations. Even before the Manchu invasion began, the Manchu leaders were larping as Chinese rulers. Chinese culture always won.
But in England and the West in general, China found an adversary that could defeat them militarily, and which had no interest in adopting their culture or civilization. Quite the contrary, the new foreign invaders were disrepectful of Chinese culture in a way that was new and shocking.
Tens of millions of Chinese died during the Manchu invasion of China. The Qing forced every Han Chinese male to shave their forehead and wear a queue on the threat of death, but that's apparently not humiliating.