I do wonder, respectfully, whether some of the people posting here live and work with a large number and variety of people?
I work in a large institution, with people in lots of roles from manual to senior professional. Lots of backgrounds, lots of personalities, lots of strengths, lots of (to me) oddities.
I can promise you that some of them work, socialise, speak, cope, grieve, emote in ways that would raise eyebrows. Whose eyebrows? Well I behave in ways that can surprise colleagues, and colleagues behave in ways that can surprise me. I see some people's bedrooms in their Teams meeting and think, normal. I see others and think, unexpected.
All this digging around with she had teddies in her room, her dad helped her with HR, she sulked a bit ... So what? If you see a lot of a variety of people, I don't see how you can possibly see her as some extraordinary outlier. If Letby's behaviours before arrest are really red flags for serial killers, I'm amazed I've lasted so long.
That's not to say, she's normal and can't be a killer. It's just to say, her behaviours in themselves are really not screaming killer, so we'd better hope the medical evidence is robust.