Your logic is wrong - a Denmark sized group of Chinese people is probably all it takes to operate their solar panel producing factories.
The reason Denmark can't do anything isn't because there are few of them, it is because Denmark isn't a significant industrial cluster for energy technology and innovation. For example, India has more people than China and they aren't in a position to do much unless there is some sort of tech breakthrough that hasn't made it to my notice.
Denmark basically invented modern wind power and still makes a big chunk of it (though China has caught up in that area recently).
Fair enough, but the major point still stands - Denamrk's industrial policies that enable Vestas are the only way they can have a significant impact on climate change. Farmland conversion does nothing; it isn't moving the needle on what is economic and industrially scaleable. Everyone still needs to eat.