This might be a rather non-standard question, and if it's too far out there, please let me know and I'll delete it. However, I hope there's a biblical historian out there that can take this on.
I'm engaged in a conversation with an Orthodox Jewish friend of mine who sent me this list of names:
Moses (1272 B.C.E.)
Joshua (1245 B.C.E.)
Pinchus
Eli (929 B.C.E.)
Samuel (889 B.C.E.)
David (876 B.C.E.)
Achiah (800 B.C.E.)
Elijah (726 B.C.E.)
Elishah (717 B.C.E.)
Yehoyada (695 B.C.E.)
Zechariah (680 B.C.E.)
Hoshea (575 B.C.E.)
Amos (560 B.C.E.)
The historical claim is that this represents an "unbroken chain" (that is, ignoring the rather obvious gaps in time in the beginning) of Rabbis/jews going all the way back to the actual revelation at Sinai, allowing them to literally bear witness to the event today.
Ignoring that, and perhaps also ignoring the early "biblical character" names, how far back can we actually go on this list and know for certain that these people even existed, much less what they believe?
Any thoughts on how this list was created?
The list is loosely based on Mishnah Avot 1:1, an ancient Jewish text from the 2nd century. It reads, in part:
משה קיבל תורה מסיניי, ומסרה ליהושוע, ויהושוע לזקנים, וזקנים לנביאים, ונביאים מסרוה לאנשי כנסת הגדולה
Moses recieved the Torah from Sinai, and transmitted it to Joshua; from Joshua to the Elders, from the Elders to the Prophets, and the Prophets transmitted it to the men of the great assembly. [translation mine].
This list is essentially that, with more detail.
Anyway, it's very difficult to determine when names in the list go from a mystery-shrouded past to historical reality. Our oldest Jewish sources are generally 1st century (Josephus), with some non-comprehensive ones earlier, like Maccabees. The earliest one I'd say likely existed is Shimon HaTzadik, who was the high priest when Alexander the Great rolled through. But he seems shrouded in legend when we first hear about him. And there's no really good reason to draw a hard line there. The challenge is that there are no secular records of most of this era, so corroborating Jewish narratives is impossible. I'm inclined to think that Ezra was historical, too, but beyond that it gets quite shadowy.