I know there are several versions of Baptist history, including the one that likes to connect Baptists with earlier independent Christian groups. My source on that would be J.M. Carroll and The Trail of Blood. The only problem with that one is that connecting the dots, so to speak, requires a lot of speculation, without any really credible documentation. For one thing, there is quite a gap of time and space between many of the groups that get connected, and for another, many of the beliefs of some of those groups are as far off the mark from a Baptist perspective of the Christian faith as the RCC. Baptists, for the most part, reject women pastors and church leaders, and they reject a Pentecostal interpretation of the Holy Spirit, and both of those things play a dominant role in the life of many of the groups through which the history of a "preserved" church would have to go.
Documented history says that the first distinguishable "Baptist" churches appeared among English Separatists in Holland around 1609. They were the result of a brief blending of Anabaptist and Separatist theology, the latter being developed as a reaction to the disappointment over the Church of England not moving forward in theological reform after separating from the RCC. Since the Church of England had been around for 75 years at the time, it is not likely any of the Baptists who separated had been part of the RCC, so the statement that Baptists, as a movement, were never part of Rome is true. However, many people did leave the Catholic church to join Baptist churches over time. So, in terminology, though they are a part of the overall Protestant reformation, specifically, Baptists did not intend to reform either the Catholic church, nor the Anglican church from which they separated.
I believe that, along with the Protestant Reformation, Baptists were indeed a prophetic voice used by God to steer Christ's church back to its spiritual and theological roots, among others. Though influenced by the Anabaptists, I do not believe it is historically feasible to trace Baptist history and origins back through the Anabaptists, again because of the differences in theology and practice, of things which Baptists have never historically accepted.
I am not aware of any Baptist group that has formed a layer of structure that holds any ecclesiastical authority to qualify and license ministers, or conduct church business, like the Methodists or Lutherans have. As I understand it, each Baptist church, even in the more "liberal" Baptist groups, is independent, autonomous, calls its own pastors and leadership and determines its own doctrine.
It is probably something that belongs in another thread, but I believe Baptists are well into the process of losing the prophetic voice they have had since their founding.