Did witches exist

Yes. "Witchcraft" is nothing more than using the powers of the mind to manifest your desires in reality. The ancient people who worshiped the old gods (Zeus, Amon Ra, Odin, Thor, Aphrodite, etc.) knew this well, since their lives were based upon nature. There were many deities who instructed mankind on the ways of witchcraft.

Christianity turned these original gods into the "Demons of Hell" and made witchcraft "evil" in order to gain complete control of society and scare people away from this ancient knowledge.