Man power with all the infrastructure let the China to become the manufacturer hub of this world but since covid attack every country realized that they shouldn't be dependent on one country for everything they import so which resulted in some of the biggest companies moving their plant to other countries. Probably China may surpass US economy in the next few years but I swear that US is not going to let them to make it is easier.
That manpower is also the cheapest as far as I know, not to mention the money trap that China puts other small countries in to create a new Silkroad. But, China beating US when it comes to economy is still a dream to be fair, the economy of China is exclusive and most of their wealth is invested in real estate bubble that does not pop because they have exclusive economy.