I find East Asians to be more Subtle on average. They tend to invest most of their social energy in family and their best friends while not caring that much about everyone else. They tend to be very closed or put on social acts until you get to know them. The Chinese are a good example. Koreans even more so.

I find Czechs to be more Subtle than average. They can seem fairly cold and indifferent when you first meet them, but they open up nicely.

The Russians are as known for mystics, philosophers, and authors as they are for icy autocrats, gigantic weightlifters, and streetwise mafia bosses.

More traditional, especially rural British people are very much on the reserved, introverted side.

The Dutch seem to be an inward oriented people. Almost all of them speak pretty good English so they can communicate with the rest of the world. Like East Asians, however, they don’t encourage outsiders to learn their language. Dutch is for communication between Dutch people.

Furthermore, I find highly outgoing Mediterranean and Latin American civilizations to be much more tolerant of less social people. They tend be less judgmental and more empathetic. Or they’re just more easy going and just don’t care as much if someone is acting a bit strange.

Africans are often soft spoken and understated, especially East Africans. Most Ethiopians, Kenyans, Eritreans I’ve met have an extremely mellow and even temperament. They are hospitable, friendly people, but without any sort of overwhelming forcefulness.

I might suppose that many, if not most societies on Earth tend to be more subtle than our own. However, most of these peoples aren’t typically in the spotlight because they aren’t looking for attention with the same intensity as the truly aggressive peoples. There are whole societies out there that keep themselves mostly out of circulation.
In fact it’s societies like these that maintain a cohesive continuous cultural identity across millennia while Loud societies lose their sense of purpose and identity.