I think this is a deeply flawed and simplistic categorization of Americans’ political sentiment.

It is an oversimplification, I don’t deny that. But just because my analysis is a simplification doesn’t mean it is wholly inaccurate or lacking in usefulness.

“Progressives” capture a broad swathe of people with different concerns and intents, very many of whom are doing just fine but appreciate the myriad systemic issues that merit address.

That’s true, although I don’t know how many progressives are “doing just fine.” Perhaps it’s many, or even most, but I don’t think anyone can say for certain. I’m not sure it matters, either, whether progressives are just disaffected people or disaffected people and their allies and advocates. The point is, despite their differences, they want radical change, and that is ultimately what puts them at odds with centrists.

most people just don’t give significant thought about their politics and their practical and lived impact on their lives.

I think that’s true as well, but I’m not really making a distinction between the people who identify with and lend their loyalty to one political tribe or the other, even if passively, and the thought leaders of said tribes.

It also means that a very large portion are not reacting to anything-- they’re just bumbling along like humans always have and it’s the incidental cascade from flapping butterflies here and there that cause the population level swings and societal changes we ultimately see.

Well, I think you might be doing the thing you accused me of and oversimplifying. I don’t think societal changes are simply a result of an incidental cascade brought on by bumbling, thoughtless humans flapping around mindlessly. Certainly some people have much more influence on societal change than others, and many people are mostly just passengers, but that doesn’t mean societal changes are merely random.