LOL! I remember reading a book where a JW knocked on a New Yorker’s door in the 1960s and said,”God has a message for you,” and her mother said, “Tell him to send it by Western Union.”
I don’t think they are true Protestants, but as you say, they came out of that weird 19th century period where there was a surge in strange spiritualist cults coming out of areas in the “Burnt-Over District” (Upstate New York, source of Mormonism) and others where there had been heavy Protestant camp-meeting style revivalism and not a very effective institutional Protestant presence.
That is, the mainline churches were perceived as being upper-class, and the camp-meeting folk were not, but because there was no continuing church presence, they were up for grabs by whoever was the next charismatic speaker. Spiritualism was the 19th century equivalent of New Age; think of all the many 20th and 21st century cults that have been based on a combination of New Age and some vague remnant of Christianity or Judaism, and you’ll get a realistic view of the source of the Mormons, Jehovah’s Witnesses, Christian Scientists, etc.
Ha, one of my Uncles was butchering a deer in his garage one day long ago when a couple of them came to visit. He emerged fairly well covered in blood, knife in hand and asked “Can I help you?”. Never heard from them again.
The 19th Century American-based religions (Mormons, Jehovah’s Witnesses, Christian Scientists, etc.) are not theologically Protestant or orthodox Christian. However, the style of their worship, their rejection of any and all post-Apostolic practices, and their focus (LDS and JW, not Christian Science) on personal conversion are rooted in the evangelical, camp meeting Protestantism of that century. To an uninformed Catholic or Jew, members of these groups would seem to be a Protestant cult.
Jehovah’s Witnesses are not Protestants. JW’s believe all churches are of the Devil and only the Watchtower Society/JW’s are the true Kingdom of God.