There's a massive debate on the level of the Roman economy. The older thinking under Finley was that it was a primitive economy but newer scholars are contesting this blanket statement. It certainly wasn't a sophisticated system but most agree that from 200 BCE to 200 CE it saw moderate but ultimately unsustainable growth.

As for how the ancients perceived it, well the modern science didn't start until Smith's Wealth of Nations. The origin word oikonomikos is to do with household management. Ultimately we lack so much data on ancient economies forcing us to anchor on the few scraps of data and build the rest on conjecture or modern economic models. It's incredibly nebulous.