You are both not good at reading. Geralt is THE Witcher, that's what Sapkowski intended with this title. Everything that happens in books we see through his lens. There is a reason why Sapkowski wrote another 2 The Witcher books after the Saga final with Geralt, not Ciri, as protagonist, even tho he died at the end. It might shock you, but the reason is The Witcher is Geralt. There are other witchers, there are sorcerers,kings, there is child of Elder Blood, but he is The Witcher. Just like there are a lot of barbarians but there is one Conan the barbarian. It's beyond retarded that there are people that don't get it.
Don't try to be Sherlock when you didn't even do your homework.
While Geralt is the titular witcher of the books, he is not the only witcher in the universe, nor was he originally intended to be the protagonist in the first game. The early concept was to use a blank slate for the protagonist of the game and the few screenshots showed some dude with a short Gotrek-like red-haired mohawk. This was featured in a gaming magazine and it was before times when you could find everything on the Internet, so I doubt it is possible to find now. Especially when you have a planty of stuff from the games flooding the search results. This was later changed to Geralt. That's why the first game has the witcher medallion from the Wolf School on the cover, instead of Geralt himself (unlike the latter two):
So? I am skeptical they have a good explanation. Just as I am not buying their bullshit that they always intended Ciri to be the main character of the series. I mean, these covers should make it obvious who the real main character of the series was:
You want to make Ciri protagonist, fine. Then call it something like The Witcher Saga:Lady of Time and Space. That's how you differenciate it form the main story Arc with respect for fans and source material. They've already succesfully done that with The Witcher Tales. But not now, because now it's not to entertain us, it's to make a statement.
They're being desperate is what this is. After Cyberpunk 2077 they don't trust themselves with creating a good narrative with a blank-slate witcher. That's why they are using Ciri and The Witcher brand as the continuation of sorts. It's their attempt to Return to Form™.