Communism has not objectively failed. USSR managed to improve lives of millions of people, and the transition to capitalism has been an abject disaster. Claiming that the fact that USSR is no longer around is a failure of communism is a nonsensical argument though. Plenty of capitalist regimes fail, yet we don’t see you saying that capitalism failed because of that.
Meanwhile, saying that PRC is capitalist shows a profound lack of understanding of the subject on your part. If you care to educate yourself on the subject then you could read this book redletterspp.com/products/the-east-is-still-red
USA got in the dominant position after WW2 not because of capitalism, but because it was the only major power that wasn’t directly involved in the war and hasn’t been destroyed in the process. The world order that US built is collapsing as we speak.