This might be common knowledge in Spain, but one thing I learned recently is that Virgin Mary worship had very grassroots origins. She was being worshiped as far back as the previous millenium, but the Catholic Church waited until the 19th century to make immaculate conception a dogma. There’s a push-and-pull of the church repeatedly getting infused with the energy of local practices like this, which it was sometimes ambivalent or hostile to if they seemed to reflect different values.