It was absolutely a catch all for what was part of AD&D at the time. Gary had no curation or grand design plan, he just incorporated what he thought was cool and what elements AD&D had at the time. Which is why Things like the Cavalier or Samurai were part of the setting. The same thing was true of Greyhawk in the FtA incarnation and the Living Greyhawk one. Remember, Greyhawk was the default setting for 3e and thus everything not specifically made for another setting was possible.
Aarakroca absolutely were a part of the world since the Fiend Folio (1981). Half Dragons have also been a part of the setting since 2e, there are explicit half-Greyhawk dragons!
The idea that Greyhawk is some bastion of OSR sensibilities where Fighting Men are Men and demi humans are limited to single-digit levels is revisionist history to the highest degree. It's a reaction to 3e's use of the setting in the PHB and grognards not being willing to accept half-orc sorcerers. And as the echo chamber has grown more insular, it has reached the point where the only things that should exist in Oerth are just the stuff in the AD&D PHB, DMG and MM (well, maybe not psionics, and possibly not bards, jury's out on that).
And if that is your Greyhawk, then cool; your version saw print 40 years ago. But AD&D isn't published anymore, and a D&D setting supports the current edition of the game. If you want a Greyhawk encased in amber and unchanged, you already have it. The rest of us want a modern take on the setting.
Yes, you can say any myriad of races were IN the world of Greyhawk, but whether they were intended as common members of adventuring parties is another thing entirely.
ADVANCED DUNGEONS AND DRAGONS™ was humanocentric. The same level limits and class restrictions applied to Forgotten Realms and Dragonlance too. Greyhawk didn't do anything different than either. And drow were playable in Gary's own Unearthed Arcana.
And it was moot by 3e anyway. LG has no restrictions on species beyond what the RPGA did.
Again, revisionist history of Greyhawk seems to make the setting stop at the 1980 Folio.
I think you are being a little of unfair calling my viewpoint revisionist.
You've got multiple sources from throughout Greyhawk's history backing up what I'm saying.
The 1983 World of Greyhawk boxed set (Gary Gygax):
Humans are the dominant race in the Flanaess.
Living Greyhawk Gazetteer:
Greyhawk's character is very cosmopolitan...
Humans are the humanoid race that most dominates the culture and politics of the Flanaess.
Humans tend to oppose orcs, goblins, hobgoblins, gnolls, trolls, and similar races, driving them into mountains, forests, swamps, and other marginal lands.
Notice that "cosmopolitan" here means humans, dwarves, elves, halflings, and gnomes; not every race that exists in the setting.
The Adventure Begins:
[Monstrous] humanoids have very limited civil rights...
A gray area exists for unusual beings such as centaurs or pixies, who are not hated but aren't viewed with a great deal of trust, either.
You uh, do know that Aarakocra and Kenku are well, well, well established as being in the Flanaess, right?
Like. They're both from Fiend Folio, of course they're around in Greyhawk at this time. Heck, Kenku are regular encounters in UK2, and the Aarakocra are mentioned in From the Ashes (the reference cards).
As for Dragonborn, well. There's a mysterious never explored land off west called Lynn that needs a revamp to not be directly copying from another source, and given the association with dragons that seems an obvious place to put 'em. Not like anything's been published under either TSR or WotC to contradict Dragonborn not being from there.
Yes, I think you are misunderstanding what I'm saying, or I failed to articulate myself clearly (which is more likely

). I'm not saying that these races can't or don't exist in Greyhawk, but rather the chances of them being PCs are significantly low.
History disagrees. Aarakocra have been in Greyhawk since Gygax's WG4: The Forgotten Temple of Tharizdun (the Plateau of the Aarakocra). Kenku feature in both WG12: Vale of the Mage (page 62 is titled "Kenku Adventurers") and From the Ashes (on the Tamara Belongs to Me card).
See my previous comments, especially about Living Greyhawk. Existing is different than being forced into the setting in the way Dragonborn were in Faerun for example.
If something is part of the world it’s part of the world.
Wether or not you can play it is a mechanical limitation of the rules, it has nothing to do with the setting.
I think you're being a little obtuse, but maybe I am as well, so let me clarify things.
Yes, these different races can, and in many cases do exist in Flanaess. However, they are not in the majority of adventuring parties and every 7th PC probably isn't a member of one these races and is most likely Human or one of the "Demihuman" races.
Complete Book of Humanoids. A supplement like Monsters of the Multiverse was.. and what you can play in the setting was based on the DM, not the setting.
You point me to a paragraph in an official Greyhawk source made by TSR or WotC that bans what species you can play and I'll accept defeat. Otherwise it's just grognard preference masquerading as a hard setting limitation.
I'll point you towards the top of this post for that. I don't think I'm a Grognard for thinking that Greyhawk is a Human-centric setting. But, it's all down to preference right? WotC can move forward and do to Flanaess* what they did to Faerun, but then I fail to see some of the point of Greyhawk and they might as well just stick it into Abeir-Toril somewhere.
*I actually really like what WotC has done with Faerun even though I think it steals some of Khorvaire's cosmopolitan thunder.