Did we call it “pollution” back then or something else? That is, did we lump CO2 conceptually into the same category as soot from coal plants and things like that?

Society uses labels to group things together so that we can treat similar things similarly for various purposes. For example, when we talk about “education” we usually mean teaching kids in schools or colleges. Of course, there’s lots of other things you can call “education.” But if the Department of Education comes in and says it’s going to regulate technical presentations at software conferences because that’s also “education,” then you’d say: “that’s not what people mean by the word education in this context.” That is, we have a consensus about what “education” encompasses and what it doesn’t for purposes of government regulation, and seminars at conferences falls outside that understanding.

Yes, labels matter; so let's take a step back and ask why you're fighting this argument? Why does it matter which of the harmful emissions from a smokestack count as "pollution"?