The question seems to force us into choosing between saying, "these were real individuals" vs. "these are entirely made-up (read: fake) characters."
I'm not sure that is a helpful dichotomy, or one that confoms well to reality. Much of what is written in Sacred Scripture about these persons may well not have come from historical records or texts that would qualify as acceptable "source material" for modern historians, but rather, involves faithful, inspired reflection on the traditions (mostly oral, no doubt) known to the author.
But, I still believe those passages are inspired by the Holy Spirit, and are true; that is to say, they communicate real knowledge concerning true relations between God and His creatures.
Personally, I see no reason to cast doubt on the historical, individual existence of any of them, especially with respect to Moses.
Even outside the Bible, historians and archaeologists have often been surprised to discover historical underpinnings to what they had previously considered purely fictional "legends." Inscriptions have been found testifying to the historical existence of a Gilgamesh, king of Erekh (or Uruk), the hero of the Epic of Gilgamesh. There was a historical king Arthur of the Celtic Britons. Heinrich Schliemann used his knowledge of the Iliad to locate the remains of ancient Troy, and Arthur Evans' discovery of Minoan ruins confirms many elements concerning the legends about King Minos and the minotaur (including the discovery of a bull skeleton in the labyrinthine "basement" of the Minoan palace in Knossos). I could go on.