You’ve posed a question to which a definitive answer cannot be reached. The highly obstinate will insist that every word is true; the non-believers will say that none of it is true; the sensible will say that some is historically true and some consists of allegorical lessons or parables which may are may not be presented as they were actually spoken originally.
A parable is a fictional story used to teach a lesson, usually one of commendable ethics or morality. Jesus used parables and therefore told untruths to embellish a lesson. That Jonah was actually swallowed by a fish and spit out days later on dry land is likely not true, therefore not historical.
Were I a student of the Bible, I could go on forever and a day listing things I believe to be questionable and things I believe to be literally true. It would be a wasted effort as it likely would not change anyone’s beliefs.