This post is an argument for human-centric fantasy, not because Gary Gygax said so, but because tone matters. Human-centric fantasy is easier for normies (normal people outside the hobby and other adults), and even some of the participants to take seriously or respect.
Gary Gygax envisioned Dungeons & Dragons to be human-centric. I know this because I read it in the Game Masters Guide he wrote for first edition AD&D. Quote "Advanced D&D is unquestionably "humanocentric", with demi-humans, semi-humans, and humanoids in various orbits around the sun of humanity." This is very different from modern D&D.
To quote Gary again, "The game features humankind for a reason. It is the most logical basis for an illogical game. From a design aspect, it provides the sound groundwork. From a standpoint of creating the campaign milieu it provides the most readily usable assumptions. From a participation approach it is the only method, for all players are, after all is said and done, human, and it allows them the role with which most are desirous and capable of identifying with."
Gary was just getting started! The font is tiny, and it goes on like that for an entire page! He goes on to say how we have a real world full of history, fiction, science, and mythology to draw from about humans, but not so much to draw on for other creatures such as elves. This means, to quote Gary,"...the magnitude of effort required (for a DM to create their campaign setting) is reduced by several degrees." This sounds practical. He also says that works of fiction that do not feature humans as the center focus are uncommon, and so creating a campaign around non-humans will be "shallow, incomplete, and unsatisfying" unless the DM is "a renaissance man". That may have been true in the late 1970's, or maybe it was Gary revealing his own biases. The reality is that the library of fiction has blown up since then!
Let me poke another hole in Gary's argument. Fantasy and science-fiction are so common these days that you can probably ask your players what their expectations of a generic fantasy setting or story are, and you'll probably arrive at a consensus after a bit of curating. I think the best point Gary raises is "Alien viewpoints can be found, of course, but not in quantity (and often not in much quality either)." By alien viewpoints, I think we can extrapolate this to mean elfs, dwarfs, hobbits, etc. The modern iteration of the elf is a creature who is practically immortal and doesn't sleep. How can something like this possibly relate to humans? There are people in this hobby who genuinely find it ruins their immersion when players play elf characters like humans with pointy ears. Some people don't care, but some people do!
By the way, the section of the Advanced D&D Dungeon Master's Guide that I have been referencing is called "The Monster as a Player Character", and I think Gary's intent with writing this section was to justify limiting players choices of races. It shows Gary's tastes are in low fantasy. What a coincidence; So are mine! Modern D&D feels like playing A Very Muppets RPG. I've read criticisms that call it kitchen-sink fantasy because there's a little bit of everything. It lacks cohesion. There are things that are stuck into the game without consideration for whether it makes sense to stick it in. In the last 5e gaming group I was in, I felt like Eddie Valiant in the movie Who Framed Roger Rabbit. I don't like it. It's not to my taste. I imagined being a cool wizard, but I was constantly outshined by a min-maxed little kobalt with goofy personality quirks and who soloed an NPC using Strahd's stat block in two combat rounds! Two!
I was expecting a vibe like Lord of the Rings. What I got was something else. The GM was trying to run the game with a tone like Lord of the Rings, but the players weren't. One of the characters was blatantly the Green Power Ranger. One character was based off the Mandalorians from Star Wars. One character might have been partially inspired by some gangster movie. And of course, one of them was that goofy kobalt assassin who was the most powerful of us all. These are tonally distinct and tonally incompatible ideas. They don't mix. It's like mixing Peanut Butter and Pepperoni (or as I call it peanut-pepper butter-oni). The tone of one idea spoils the other.
I really like Legends of Avantris. It's a podcast of people who play D&D for the entertainment of an audience. It's distinct from Critical Role, in my opinion, because the Avantris people make likable characters and half of the CR people don't.
I would like to sincerely apologize to the cast and crew of Critical Role for the above comment.
The point of bringing up Legends of Avantris was to point out that they don't use human characters very much and their shows, no matter how good, are always tonally off. They all feel a bit cartoonish. Even Icebound, a serious podcast with darker themes, would be slightly less silly if the characters were all human. It would be easier to take seriously, and it would be easier to get into
Here's the real reason for a human-centric setting. It's about tone and personal taste. If you can play a monster (i.e. kobolt player character), then monsters aren't monstrous; They're just exotic people, like South Park Canadians. You can't have it both ways. It's hard to reconcile a setting where monsters can be monsters like in a horror genre, but also exotic people.
Human-centric fantasy isn't about limiting creativity, it's about protecting tone. Think about it like this. If you wanted to introduce something to a normie, would you be more confident if it didn't have a bunch of cartoonish looking characters? For instance, in Icebound, the cast is a small green guy with a conniving expression, a big blue guy with a crab hand, a dragon man who always looks too relaxed, and a bunny girl depicted with flattering hips. Any of these things would make a normal person give you a funny look. The bunny with the hips might make them give you a dirty look. You might feel like you have to defend your interests. Someone might think you need to grow up. I think the cartoonish qualities make the medium harder for adults to take seriously, and I think it's detrimental to the hobby.
No matter what, cartoonish aesthetics will always undermine a serious tone. Human‑centric fantasy keeps the tone grounded, relatable, and emotionally legible. It's the same reason why they toned down superhero costumes in modern superhero movies. Tone and relatability. Human characters will always have more appeal to a causal audience. They make the world easier to believe, the tone easier to maintain, and the story easier for adults to take seriously.
Related post: Seven Rules for Monsters in TTRPGs - Your Fun is Wrong