"If the slave did not come into existence until 1919, then how was it possible that prior to 1919 that anyone knew that it existed, or would have been able to foretell that it would come into existence?"
These were "running ahead" of Hojovah's celestial chariot. Kind of like the millions of Christians that expected armageddon in earlier centuries. How foolish of them to recognize that such Bible prophecies couldn't be fulfilled until after CT Russell used pyramid inches to analyze the Great Pyramid of Giza and establish 1914 as the year of armageddon... later postponed.
"Was Maria a prophetic apostate?"
Unless you have a quote where she talks about gays designing tight pants, she wasn't a prophet.