Being doubtful about historical facts is a fine and healthy state - my detailed grasp of history ends in 117 AD and is focussed on Rome, so that's not much use for Wellinghall's question here, but historiography is useful for example because NO Greek or Roman writer thought about "history" as we do. It was written by and for the elite to give examples of how (or how not) to behave. And though they sometimes said they were being truthful and unbiased that is (to be blunt) baloney.