This is true of the middle and late Republic, but after the major conquests end and the large numbers of slaves stop being imported the slave numbers decline and the migrant farmers regain power. Eventually the big plantations become patronage/taxation networks for peasant families, and eventually those become the economic base for the fuedal system.

Depending on the era you were a peasant in, you might even get the opportunity to participate in a secessio, the Roman equivalent of a general strike.