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.
That is simply not true. Manpower in China used to be cheap, but that was one or two decades ago. The wages have risen to such a level that they are now 2-3 times higher than the comparable salaries in countries such as India and Indonesia. On top of that, they are now getting strict with environmental and other regulations. Lax regulations attracted a lot of investment earlier.