I’ve had evangelical protestant friends point to the Albigensians as the “underground remnant” of true Christianity in opposition to the Catholic church of their day.
(This allows protestants to offer a timeline going back before the Reformation.)
Anyway when I explain what the Albigensians really believed, they either concede the point (and implicitly acknowledge that their pastor was misleading them about the Albigensians) or accuse me of lying for the church.
Very interesting first hand experience. I bet some of those conversations are quite animated.
Attempts to reform corruption and suffocating power in the Roman Catholic Church began with false starts and failures long before Martin Luther's 95 Theses in 1517.
Names like Jan Hus (†1415) and Girolamo Savonarola (†1498) come to immediately mind.
But the core essence of Protestantism is devotion to what the Bible actually says, as opposed to what some bishops somewhere claimed it sort-of means.
So where-ever you can see such devotion before Luther, there you might say are pre-Protestants.
But you really can't have serious Protestants until you have a lot of Bibles available, and many people able to read them, and that didn't really begin until Gutenberg's Bibles, circa 1450.
So Cathars-Albigensians could not be considered pre-Protestants, except in their "maniacal" feelings about fundamental corruption and wickedness in the Roman Catholic Church of their day.