The Witcher: Bloodborne Missed a Big Opportunity for Éile
Of the characters introduced in The Witcher: Origins, Éile has the best opportunity to break new ground in the show's narrative universe.

Warning! SPOILERS for The Witcher: Blood Origin!
^ While The Witcher: Blood Origins contained many revelations, Netflix's prequel missed a great opportunity to work with Éile (Sophia Brown). One of the biggest selling points of the miniseries is its ability to expand upon the lore in The Witcher to create compelling and original stories. Among other things, the show's promise of building up the Monster Hunter organization and the opportunity for new characters to work in an entirely different world order isn't enough.
Set 1,200 years before the original show, The Witcher: Blood Origins follows seven warriors who resist the rise of the Elven Golden Empire after a coup kills the elite warrior clans that protect three Elven kingdoms. These include Éile of the Crow Clan and Fjall (Laurence O'Fuarain) of the Dog Clan, and since they have the most personal interest in avenging the death of their peers, they have the chance to combine their essence with that of the Monster to become number one a wizard. However, despite Éile's intention to be the one to go through the dangerous process, Fjall does not comply with her wishes and takes Mixture instead.
While the show describes Fjall's sacrifice to become the first noble witcher, there's no good reason for Éile not to do so. Éile and Fjall are both fighters in The Witcher: Bloodborne with strong combat training and conditioning, so there's no reason she couldn't survive the process like Fjall did. As such, Fjall's refusal to let Éile do so is demeaning and sets the stage for the narrative in the series' timeline as there are no female wizards later, even though both warriors are physically eligible to attempt the Trials.
Éile Should Have Been The First Witcher

Éile would have made a better narrative choice for the first wizard than Fjall, even if it was beyond their physical capabilities. She was the first hero introduced in The Witcher: Blood Origins, establishing her as the focal character that brought the rest of the cast together. Structurally, this alone should make her the first witcher as an archetypal leader, she won't risk her followers for anything she won't try, and Fjall's meddling will only Weaken the effects of Éile. Furthermore, Éile had the strongest motivation to Try this adventurous process as she wants to avenge not only her clan but also the assassin who killed her sister.
Some may argue that Éile could not have been the first successful wizard in The Witcher: Bloodborne, as doing so would go against the source material and canon of the original show, where there are no female or black monster hunters. However, "The Witcher" has already shown its intentions to diverge from the original novel in season 2. So there's an opportunity for the prequel series to continue these changes and further refine the source material by including more and different The Witcher. If anything, The Witcher: Origins would have given The Witcher season 3 more leeway to do the same, but unfortunately, the show squandered that opportunity.
The Witcher: Blood Origin Should Diverge From Canon

Prequels can be adventurous and interesting for the opportunity to retrace the story of the extended series. Making Éile, the original The Witcher could have updated the show's universe to better fit the times, improving the show as a whole. The Witcher: Blood Origins had a chance to build on that strategy with Éile, but squandered her abilities and charming personality in favor of traditional strength-based white males Monster Hunter as seen in Geralt (Henry Cavill) and Fjall.
The Witcher: Blood Origin is now streaming on Netflix.
More: Will there be a Witcher: Bloodborne Season 2?