Just to give things some scale, the longest book series in WH 40k is the hours heresy. It's 60+ books. And that takes place in the 30th millennium, so it's just background to current times lore.
There are more than 300 novels to read, and that's just counting novels. There are also codexes (codecies?), other supplementary books, other game books (like dark heresy), and the many issues of the white dwarf magazine.
That's it. That's the lore. That's how much people like to hype up kirby lore despite it being a big ol nothingburger. That's why he's just so upset about all that hype and then... the big reveal. Kirby eat things.
There's also the fact that there are other potential incarnations of Kirby also wandering around the universe, except they're evil. Also they seem to be able to kill omnipotent gods somehow. And potentially create them too.
I think there was also something about Nova or whatever his name was being made by the same species Kirby is?
Which, because they're all dead except Kirby and Metaknight implied that there's something capable of killing them, too, that we've never seen.
Also Kirby probably never killed 0. It would seem he can't die in fact. And he seems to be what happens when Kirby reincarnates as evil instead of good.
The final boss of Kirby Squeak Squad is implied to be an incarnation of 0. In Japan his name is even "Dark 0."
Kirby lore is basically "Lovecraft for Kids" if you ask me. Way simpler than traditional cosmic horror, but it has the same elements.
The latest villain in the series was unusually weird, IMO
especially with the whole lab experiment treatment and cartoon biological horror moments. Also the unknown fate of the people who used its power to depart for some dream dimension or whatever.
In the last game, Forgotten Land, Kirby fights against a god level dimension warping motherfucker who corrupted all the animals and steals souls for power. After being Kirb stomped, Fecto Elfilis creates a pocket dimension to escape to that contains all the souls and warped versions of the bosses. A pivotal part of the end boss build up is a wall of flesh/psychic material chases after you, the goopy mass swarming with the faces of those it's consumed.
This isnt even lore yet - it's gameplay. Kirby is also haunted by Meta Knight, space wizards from other dimensions, and so much more. It isn't hype to just talk about what's happening in the game.
Depends on the game as the characters grow from enemies to conflicted allies who have to fight wizards and extra dimensional beasts. But yeah, they're pretty chill around each other as long as no one fucks with the Waddle Dees.
It's less about length and more about absurdity and power levels. As a rough translation, imagine if everything ever done by chaos was defeated by a single entity that ate them. That's basically how Kirby lore works.
Don't worry, most worldwide fans didn't either. Outside of first world countries few can afford such a hobby so a big chunk of the community are just lore enjoyers
I think some of them are pretty good! My favorites are the Ciaphas Cain series and Eisenhorn series. Gaunts Ghosts is also good if you want a more serious military read. If you want non-humans, check out "The Infinite and the Divine". It's about necrons (highly advanced ancient space robots/terminators).
I finally got round to listening to a bunch of 40k stuff, I've read some in the past but not a lot and it's been a while. I started with the ciaphas cain series, it's somewhat comedic at times and the main character reluctantly gets into situations thanks to his heroic reputation. Lots of fun. Now I've been going through a bunch of Dan Abnett's stuff, eisenhorn and gaunt's ghosts. They both take themselves a lot more seriously. There's like 11 cain books and 16? Gaunt's ghosts books. It's all down to preference but I've been enjoying the guard-focused books a lot.
I think it's worth getting into, but you will quickly find authors you like and ones you dislike. I think the worst part of reading 40k is that you'll find a book you like, but it isn't a part of a larger series. For example hellsreach, or rin's world.
Maybe watch some YouTube videos about the setting first to see what interests you about the lore, and then start with books about that.
Warhammer, both Fantasy/AoS and 40k, have a billion books so if that's what you want, I'd say definitely check out at least a couple of the different series. Horus Heresy was mentioned, then there's a different series about Egyptian space terminators that is highly recommended, think the book is called Infinite and the Divine, then there's all the Ciaphas Cain books, really there is an ungodly amount, and all of that is just 40k.
On the Fantasy side, most highly regarded is probably Gotrek and Felix, a guy and a dwarf that travel and kill monsters and shit.
There are a shit ton of series to choose from, you could easily spend a long time reading only Black Library if that's what you'd like.