The Table's "Appendix N" is more important than the designer's

Do you love it when a blog post or a video starts with a somewhat controversial statement and then you have to click in to see why they would post that?

Wait don't leave yet! Let me give you my prerequisite amount of context first, I promise it's worth it!
In the days of yore, Gary Gygax and TSR published the rambling, nigh incoherent Dungeon Master's Guide for AD&D in 1979. Mostly a sort of free flowing collection of essays about Gary's own philosophy for running the game, one of the more intriguing and less controversial aspects of it is found all the way at the back of the book, titled Appendix N: Inspirational and Educational Material. In it, Gary lists a wide variety of material, mainly pulp Sword and Sorcery fiction, that served as a helpful list of media to consume to understand the fictional space that D&D occupied.

Now a days we tend to use Appendix N as a catch-all term, and a lot of game designers have their own personal Appendix Ns for their games. And that kind of thing can be helpful, especially if you are reading a new game and having a hard time conceptualizing it or grasping what it's going for.
But, something that doesn't get talked about at all, is the sort of personal Appendix N that you and your individual players are bringing to the table, and how that shapes the game we all play.
A Confession
Alright I'm going to level with you all; I haven't read anything on the above Appendix N from the DMG except for Lord of the Rings. I haven't read Conan, Elric, Dying Earth, or Fafhrd. I am a fake OSR fan (I say in an incredibly tongue-in-cheek manner). Some of these things I know about in a second hand fashion, or through a sort of cultural osmosis. Some of these are on the reading list, I'm gonna get there! But I have to imagine in the year of 2025, I am not the only one. Most of these works were pretty niche in their day, and with the explosion of heroic and high fantasy, they have only gotten more obscure.
So when my players and I use Old School Essentials to play The Halls of Arden Vul, we have a totally different cultural context for this kind of game than the folks at TSR would have had. We're playing an OSR game without any backing in the Sword and Sorcery genre going in, and that does change how we view and interact with the game! To the point where ultimately, the Appendix N that got written in the book doesn't matter all that much.
A More Modern Problem
In my Pathfinder group, I had a player who really liked the idea of playing a vampire character. Not a surprising ask, a lot of media over the last few decades has portrayed vampires as misunderstood tortured souls, rather than the monstrous villains of Bram Stoker's Dracula. The Pathfinder interpretation is pretty classic (and kind of terrible). Vampires are useless in sunlight, need to drink blood to live, and in response they get some cool magical and transformation abilities. But when my player wanted to play that vampire, he wasn't thinking about Dracula, he was thinking about this;

This isn't really his fault, nor is it Pathfinder's! The term vampire has become unbelievably broad (as have a lot of fictional terms we lean on in the RPG space). But reconciling the gap between his mental image of a vampire and what a vampire is in Pathfinder took some time and explaining! And any time you are playing a game with a setting that is different from your perceived default, it creates mental overhead to keep yourself immersed in that setting.
Okay but what do I DO with this information
First of all, let's talk about what NOT to do;
- Don't give your players homework. Nobody is reading one or more novels just to play in your campaign; most players will barely read the rules
- Don't berate your players for not fully understanding the vibes and setting of the campaign; they're nowhere near as invested in this as you are as the GM
- Don't punish players at the table when their play is based off of misconstruing or misremembering certain setting details. Be ready to re-explain and let them walk back their actions
Instead, do these things;
- Give players handouts on the important setting terms they need to know, so that they have handy references during play
- Spend some time in session 0 asking players what comes to mind when certain terms get said; do we all have the same idea of what an Elf is, or how Dragons work?
- Try to find common cultural touchpoints within the group that you can reference. Being able to say that something "works like X" only works if everyone has seen X!
Hopefully this advice can help immerse your table in the fiction more and create more memorable play, without expecting your players to have read dozens of fantasy novels before the game starts.