Something that surprised me when I started reading about this case is that there is not a single piece of hard evidence that any of the children was assaulted or murdered.
No autopsy or inquest declared "This child was the victim of homicide, we just need to find out who did it".
In other words, the alternative to "Lucy Letby killed them" is not "Somebody else killed them, but nobody could have, therefore it must be her". The alternative is that they just died. These were, after all, very sick children. That's why they were in hospital.
At one point the prosecution noted that the children who died were, pretty much without exception, the sickest ones on the ward. This was used as evidence of how evil LL was: "She deliberately chose the weakest so that they would be most likely to die from what she did to them". But this is absurd logic. These children were also the most likely to die anyway.
The fact that the prosecution thought this was a great argument suggests to me that the groupthink was well under way. Once you decide that there is a pattern somewhere, you will find confirmation of it everywhere, even if it's just chance among noise.
We were told at the trial that 15 children died and LL was on duty every time. But we weren't told that there were several other children who died when she couldn't possibly have been involved. Is anyone looking for a murderer in those cases? Why not? (Answer: Because of someone's interpretation of statistics. But statisticians notoriously tend to agree on very little.)
She might have done it, but the more I read about the case, the less it looks like "beyond a reasonable doubt", which is the standard that applies — especially when, as mentioned above, there is no independent direct evidence that a crime was even committed.