That is a huge subject but
Historicity of the Bible - Wikipedia is helpful.
"Modern professional historians, familiar with the phenomenon of on-going historical revisionism, allow new findings and ideas into their interpretations of "what happened", and scholars versed in the study of texts (however sacred) see all narrators as potentially unreliable and all accounts - especially edited accounts - as potentially historically incomplete, biased by times and circumstances."
"By the end of the 19th century the scholarly consensus was that the Pentateuch was the work of many authors writing from 1000 BCE (the time of David) to 500 BCE (the time of Ezra) and redacted c. 450, and as a consequence whatever history it contained was more often polemical than strictly factual - a conclusion reinforced by the then fresh scientific refutations of what were at the time widely classed as biblical mythologies."
".. until Adam Sedgwick, the president of the Geological Society, publicly recanted his previous support in his 1831 presidential address: "We ought indeed to have paused before we first adopted the diluvian theory, and referred all our old superficial gravel to the action of the Mosaic Flood. For of man, and the works of his hands, we have not yet found a single trace among the remnants of the former world entombed in those deposits." All of which left the "first man" and his putative descendants in the awkward position of being stripped of all historical context, .."
Gunkel's position is that: "if, however, we consider figures like Abraham, Isaac, and Jacob to be actual persons with no original mythic foundations, that does not at all mean that they are historical figures. ...For even if, as may well be assumed, there was once a man call "Abraham," everyone who knows the history of legends is sure that the legend is in no position at the distance of so many centuries to preserve a picture of the personal piety of Abraham. The "religion of Abraham" is, in reality, the religion of the legend narrators which they attribute to Abraham."
Well, it will be a long post even if I choose from that article, so I would request all interested to go through the article themselves.