You realize she didn’t write about slaves right? She made the main character a slave owner and had a plot point about how much the slaves love being slaves and dobby is just weird for not wanting to be a slave.

Don’t deprive yourself of happiness to spite her. That being said the books have several reasons to not read them on their own merits. Don’t forget “dobby is weird for not wanting to be a slave” is an actual plot point in the books. Not to mention the goblins. If you want to revisit a beloved fantasy series, give LOTR another read/watch.

With only 4000 guard I’m sure they were able to be selective with who they sent.