I do like to define witchcraft, but it is more along the lines of witchcraft originates in a folk sorcererous rebellion against medieval christian church and feudal prohibitions and abuses rather than as an ancient pagan priesthood. It evolved by responding privately to evolving legal and ecclesiastical feedback and internally in unconnected small secret groups. After the laws relaxed. between 18th and 20th century, growth happened from transmission of information in a variety of cloaked or secret arenas. Mid twentieth century when the spiritualist and other new thought churches campaigned for repeals of the laws against claiming to practice magic. At that point, witchcraft emerges and begins to develop as a community with public avenues of dialog. Now rebellion as a force of evolution of witchcraft practices takes a back seat to efforts towards enrichment and exchange.
So how this plays out in an over simplified summary. A person is accused of doing some kind of folk magic or pagan idolotry in medieval times. The resident or visiting church authority tries them as a witch. Details of how they (supposedly?) practiced as a witch spreads either by word of mouth or by print. Others wishing to rebel against horrid conditions (bathing was illegal and immoral! The feudal lord could rape your wife legally!) copycat the “instructions” given from the trial (and church manuals for witchfinders and admonishments against witchcraft that include details of what not to do). These are not entirely invented by the church as one can see classical, biblical and folk magic descriptions of the same sorceries sans the anti church specifics. Most clearly repeated are inversions of and counters to church magics, sorcererous solutions to feudal poverty of resources and freedoms, animal features, familiar spirits, and the witches sabbath. As laws relax we see less anti church magic and more development of a separate spiritual direction drawing on diverse sources: Folklore, grimoires, classical myth, and local myth and legend, new spiritual movements, fraternal orders, available materials and local landscape features and sacred sites, and folk magic traditions. Print itself being a powerful form of exchange between distant witchcraft traditions. A great example is the influence of Leland’s treatise on a very small local sect of Italian witchcraft Gospel of Aradia on British traditional witchcraft. The monumental repeal of the laws mid 20th century lead to the witchcraft revival we participate in today.
Something I didn’t barely address, paganism is an entirely different kettle of fish…well not entirely. But tangential.