The Pope would have been very, very distant from any backwater Frankish town. Christianity was highly localized at this period, in a backwater village it'd be notable if your average peasant had a basic grasp of Christian doctrine (for instance, one of Charlemagne's major reforms was to ensure that parish priests could read the mass and explain the Lord's Prayer, think of what this implies down the line). The Pope had very little power, and was largely under the control of the Byzantine empire. Local bishops and monasteries were far, far more important (and the bishops and leaders of monasteries would be drawn largely from local nobility). I doubt anyone in your village, including the priest, would have been aware of the affairs of the papacy at all, or at best only in very distant terms.

In fact, the period you've chosen marks a point of transition for the papacy. Sergius himself was embroiled in a conflict with the Emperor which signals the continued breakdown of that relationship, culminating in the coronation of Charlemagne. We're also right before the advent of the Anglo-Saxon missionaries who were vital in the Christianization of Europe and who placed a high value on the authority of the Pope (thus ideas of papal supremacy in some degrees came from outside Rome itself). At the end of the century, Charlemagne's religious reforms greatly consolidated and standardized Christian practice and provided the stability which enabled more centralized control. This all sows the seeds which will flourish in what is generally considered, not unproblematically, the height of the Papacy, the 12th and 13th centuries specifically Innocent III.

wedgeomatic answered your question about the backwater Frank but I thought I'd note that to an average Roman guy the pope would have been a familiar figure, embroiled in local politics (and likely from a local aristocratic family, though Sergius wasn't) and actively involved in the life of the city, both civil and religious.