But the actual scientists, historians and so on are super careful in my experience to say “we don’t know” or explain the limits of their understanding so I don’

But the actual scientists, historians and so on are super careful in my experience to say “we don’t know” or explain the limits of their understanding so I don’t really understand what you have a problem with beyond poor teaching and poor lay interpretation. Even in popular media appearances, for example I enjoy the long running radio show ‘In Our Time’ which covers a lot of this ground with a lot of academic guests who are almost infuriating in their care to spell out the limits of what we do and don’t know. The point also should also be made that the burden of proof should be on the claimant. It’s perfect reasonable to take crackpot theories and say “there is no evidence to support that this is true” rather than “we don’t know”. And again in my experience it’s crackpots like Hancock that try to dissemble about how much we actually know.