In short, China endured a 'Century of Humiliation' which has sunk very deep into its national soul. The UK forced the Opium Wars onto China. In WW2 20,000,000 Chinese civilians died. During the Cultural Revolution the entire country and social order was upended. Under Mao Tsedong during the Great Leap Forward in the 4 years around 1960, 15 - 55 million at least died of starvation.
China has felt humiliated to the bone. It was humiliated in a way that is appalling and the West has a lot of responsibility for that, though certainly not all.
Since the economic reforms begun under Deng Xiaoping in the 1980's, China has turned into an absolute powerhouse. It's transformed, and the population is far better off materially.
Under Xi Jingping, who rose up with the reputation as being a diplomat and (iirc) a peacemaker but turned out to be an expansionist, China has been consolidating and extending its power in the world through economic means, quite often unpleasantly.
Historically, China flipflops between one extreme and the other. It's not the only example, but the Covid debacle sums it up - denial of its existance, then total control leading to economic and societal stress, then total removal of all controls. No moderation.
Many, most people in China are better off, but Xi Jingping is aggressive and a lot of popular media demonizes the West and the US. Why? Because it's the only big and credible rival to China. China needs Western trade, but it resents that. It wants to be self-sufficient or to have the upper hand.
China and the US are the Big Two now. Frankly Russia's influence is malign, but it's no longer in the same league as in the 1960's or 1970's. I think myself that China is doing a lot of work quietly to gain more influence over Russia, who needs China far more than China needs Russia.