The Witcher screenwriter Artur Ganszyniec gave an interview to CHIP. During the conversation with the Polish publication, he shared memories of working on the project.
In this game, CD Projekt RED used a plot device involving amnesia. Today, when many know Geralt of Rivia, this might seem like not the best decision. However, in those years, the word "Witcher" meant little to anyone.
Artur explained why the use of amnesia was justified:
Today it's easy to talk about it because everyone knows "The Witcher". The whole world knows who Geralt is. But if we had to make the first game again in a world where the audience is not familiar with the brand [The Witcher], we would still need to somehow introduce the character [...]
The protagonist's amnesia became a convenient entry point. Moreover, the screenwriter notes, if Geralt remembered Ciri, then the events of "The Witcher 3" would have started immediately:
Perhaps amnesia wasn't the best solution, but Geralt had to be introduced somehow. It also helped that Geralt didn't remember Ciri and Yennefer. If he had remembered them, "The Witcher 3" would have started immediately: he would have gone after either Ciri or Yennefer. And we didn't have the space for so many characters, nor the capabilities for so many storylines.
Artur Ganszyniec also reminded that the first The Witcher was not made from scratch. Earlier script drafts suggested that Geralt would be an NPC, not the main character. At a certain stage of development, the game's creators thought they would give the player the opportunity to create their own witcher:
The first "The Witcher" was based on earlier script versions where Geralt was not yet the main character, but acted as an NPC. The main character was supposed to be a witcher created by the player — Berengar. When I joined the project, there were already locations, situations, and characters that needed to be used. This also tied our hands. There was no room for Ciri and Yennefer there.