You know, if more Americans watched Chinese movies, they might understand films like The Great Wall better. I'm more of a Japanophile myself, but I watch a good number of Chinese epics. Netflix is loaded with them, and some of them are quite good.
The thing you need to understand about Chinese culture is that the ideal of working for the benefit of the whole has been around for a lot longer than Mao Zedong's Cultural Revolution (communism, if you didn't learn about Mao in school). The other thing you need to understand is the Chinese love for tales of mythology. Chinese culture has been around for a very, very long time, so they've got a lot of them.
Now, before we get to the idea of whitewashing, I'll say up front, I disagree. Matt Damon plays a white dude who tries to get to China to trade for gunpowder. Despite being a highly skilled mercenary who is mad down with the bow and arrow skills, he loses all but one of his cohort, only to be taken into custody by the Chinese Army at the eponymous wall.
Without revealing any spoilers, I'll say that Damon's stonehearted mercenary is ultimately swayed by the amazing qualities of the Chinese people to connect and fight a shared enemy. He learns that there is much more to life than just fighting for food and money. I'm not suggesting that China has been this oasis from pain and fear and life as we now it all this time, nor that communism is a fix for our ails, but this is what drives a primary element of Chinese culture if you're going to watch these films.
On that note, if you want to see some subtly subversive Chinese film making, check out Chronicles of The Ghostly Tribe. On its surface, it looks like a love letter to the Cultural Revolution, but just check out the overtly hyper-positive attitudes and glassy-eyed recitation that makes it more clownish than oppressive. It's not a bad film, either.
The only thing I want to say now is that you should give this film a chance. It's an epic fantasy that might even be a little too short to tell the entire tale, but it works. You can even skip the beginning bit right up until they get to the Great Wall. That's where I would have started the film with a short, explanatory preamble.