I don't like the (originially) pejorative term "Protestant" either, but all Christians coming out of Western Europe have ancestors (spiritual and genetic) once under the Bishop of Rome.
Read your history...American Baptists date back to England in the 1600s, breaking away from the official Church of England--which was one of the 3 original Protestant groups (Lutheran, Reformed (Presbyterian), and Anglican).
A fourth catch-all group, the Radicals (also called "anabaptists") is NOT the direct spiritual ancestor of modern Baptists, rather of pacifist groups like the Mennonites.
In every-day usage, any Western church, evangelical, baptist, Bible, etc., not Roman Catholic, is Protestant. And in fact, ALL stem historically from the Reformation started by Luther, like it or not.
It's a total myth that baptists had survived in Europe as any kind of body from before the 1500s Reformation. No self respecting scholar finds any evidence for that.
Cardinal Hosius (Catholic, 1524), President of the Council of Trent:
"Were it not that the baptists have been grievously tormented and cut off with the knife during the past twelve hundred years, they would swarm in greater number than all the Reformers." (Hosius, Letters, Apud Opera, pp. 112, 113.)
The "twelve hundred years" were the years preceding the Reformation in which Rome persecuted Baptists with the most cruel persecution thinkable. Sir Isaac Newton:
"The Baptists are the only body of known Christians that have never symbolized with Rome."
Mosheim (Lutheran):
"Before the rise of Luther and Calvin, there lay secreted in almost all the countries of Europe persons who adhered tenaciously to the principles of modern Dutch Baptists."
Edinburg Cyclopedia (Presbyterian):
"It must have already occurred to our readers that the Baptists are the same sect of Christians that were formerly described as Ana-Baptists. Indeed this seems to have been their leading principle
from the time of Tertullian to the present time."
Tertullian was born just fifty years after the death of the Apostle John.