While literary sources were always produced by aristocrats, they still give a window into their times even if it's biased, so we know some things about some job

While literary sources were always produced by aristocrats, they still give a window into their times even if it's biased, so we know some things about some jobs. But also since the mid 20th century there's been a movement in history to learn about the daily lives of everyday people of the past in every period including Rome. Combined with archaeology, we can learn some things, so while we don't have a perfect picture of life for the many free Roman citizens packed into their insulae doing their jobs, there's been work and progress on filling that in, esp. using archaeological sources like Pompeii.