

I’m going to have to read The Blazing World now. I’m surprised I haven’t heard of it.
Well, if you include Margaret Cavendish’s The Blazing World (1666), you would have to put Johannes Kepler’s Somnium (1634) and Lucian of Samosata’s A True Story (2nd century AD) ahead of her.
I’ve listened to “A True Story” years ago but can’t remember any of it. Reading the synopses, I think all three are closer to fantasy than Sci-Fi. So I still Put Frankenstein as the first true Sci-Fi book.

The wizards had indoor plumbing starting in the 1700s. Most of the world didn’t have indoor plumbing until the 1800s. It would be hard to read the books and not know Hogwarts had plumbing. Your bad example notwithstanding, yes the wizards are ignorant of a few things that make no sense even though they use magic for every mundane thing, and it makes less sense since children would have to completely rely on their parents for any magical utility until they were pretty much grown. It doesn’t take away from the story, but if she did the worldbuilding like Tolkien, she probably would have noticed this and made small adjustments.