Oh, but it was conmoditized even then. Roman society was suprisingly „modern” on many fields, and their approach to art was no exception. Rich paid the creators to create such art on their properties to increase their value.
Relatively speaking, they were most numerous within Rome, but they also owned lands they had lower class people and slaves farm for them that they sometimes visited.
Wealth accumulated over generations. In that time, if your great-great-great grandfather had a piece of artwork, there was a good chance it was yours now.
We have negative stereotypes of the past, and there were periods of history when that was true, but there were advanced periods too. The Bronze Age empires were pretty impressive until roughly 1300 BC. We had a dark age for a while. The Roman Empire was very impressive. Then we had a dark age for a while.
And you also want to think of the social structure. Rich people employed poor people in households. Even if I owned nothing personally, I'd be exposed to art in my master's household.
Art is just a thing we expect to see now and is easily reproduced. We are surrounded by it. This is why I chose "commoditized".