It's a little nuanced. We know about some aspects of the average Roman citizen's life: the details of their class and labor statuses, their political enfranchisement, the effects of the Roman economy on their livelihood, urbanization trends through the Republic and Empire, etc. We also know a decent amount about what they ate, what they wore, etc.
We know many of these things either because they're discussed in comparison to an actual subject, or via inference with described subjects (i.e. descriptions of the lives of political candidates, bureaucrats, soldiers, slaves, and lesser sides of noble families).
We know many of these things either because they're discussed in comparison to an actual subject, or via inference with described subjects (i.e. descriptions of the lives of political candidates, bureaucrats, soldiers, slaves, and lesser sides of noble families).