The more fundamental point is that assuming equally sound governance (a big assumption of course), the natural size of the Chinese economy is around 4x the natural size of the US economy.
Does that matter? Not really. "US" and "China" are ultimately just arbitrary labels.
Yes, that too of course. Though I'd argue that population alone is nothing, as China's 20th Century history demonstrates quite clearly.
It's a country's government and legal system, combined with its human resources (both aptitude and education), that dictate whether its population will be an asset or liability. Hence my focus on their human resources' massive numbers advantage
Does that matter? Not really. "US" and "China" are ultimately just arbitrary labels.