You know some of the stuff Marisha said on bts the other night made me really start thinking about how unusual and honestly really important Keyleth is as a character. Like Marisha said, Keyleth is one of very few charactes I've ever seen who is incredibly unsure of herself and yet is still allowed to fulfill her character arc of growing into a leader, without ever entirely losing that uncertainty; and this is probably one of the things that a lot of people don't like about her.
I think it goes further than that, though. Keyleth is, by the end of the end of the series yes but even throughout, one of the strongest characters in terms of both physical and magical power. She's incredibly versatile--she's a caster, but using her wildshape and especially her elemental forms she can effectively become a secondary tank. She can act as support by healing her teammates in one breath while dealing absurd amounts of damage in the next. Her potential in terms of sheer damage per round is immense by the end of the series. All of this is acknowledged multiple times by other party members. And yet, she's still anxious, she's still uncertain, she still doesn't always have the best handle on keeping her emotions in check. She still stumbles over herself and makes mistakes and is still so clearly learning through the whole series, how to be a leader, how to be herself even.
But she's allowed to be these things. Both the narrative and the other characters support the fact that she can be all of this--she can be emotional and afraid to lose her friends while at the same time utterly obliterating her enemies, she can be rash and angry at the same time as being uncertain and terrified, she can faceplant in lava and collapse sobbing from exhaustion one day and eviscerate the mind of an ancient green dragon the next. One does not preclude the other. And I think that that grates on some people, because we are so used to seeing our heroes as being confident, born leaders, people who don't need to grow into themselves or who have already done the messy parts of that. Some people don't like seeing an unsure, emotional young woman who is still in the process of learning stepping into a role with this much power, both magical and societal.
But it's for this precise reason that Keyleth has the potential to be an inspiration to people. She's imperfect, undoubtedly so. But she's allowed to have those fears and those doubts that we have in real life, and shes still allowed to be strong, to be unquestionably important to her group even as she experiences the growth that is necessary for anyone to develop into a leader, even if she hasn't quite got to that point yet. We've got plenty of arrogant, self-confident heroes already. Keyleth is something different--someone who is a little more like us, who can show us that yeah, maybe you're afraid and uncertain and you mess up sometimes, but you're still strong and important and worth other people's time and respect. If they aren't mutually exclusive in Keyleth, then they aren't mutually exclusive in you either.