Post History

There's a lot in this question, including some assumptions on the dating of some of the events in biblical texts, which are arguably separate questions in and of themselves. But sidestepping periphery issues:

## Internal (and external) evidence examples

The earliest biblical reference to the Hebrew language calls it "the language of Canaan" (Isaiah 19:18). It is elsewhere called "Judahite" / "Judean" (or "Jewish" --> often translated "the Jews' language" or "the language of Judah"), in contrast to Aramaic (e.g., 2 Kings 18:26, 28; 2 Chronicles 32:18; Nehemiah 13:24; Isaiah 26:13; 36:11).

As another interesting example of internal evidence (there are others, including within the book of Joshua):

> He wrote there on the stones a copy of Moses’ law, which he wrote in the presence of the children of Israel (Joshua 8:32, WEB).

We should not underestimate how much text could be fit on steles based on those which have been recovered.[^1] 

As an example of external evidence, we have the extant [Siloam inscription](https://en.wikipedia.org/wiki/Siloam_inscription) which commemorated the construction of Hezekiah's tunnel, completed in roughly 701 B.C., which was written on stone *in the paleo-Hebrew script.*

## Summary of the evolution of the Hebrew alphabet

> The family of languages to which Hebrew belongs is grouped by linguists in a phylum called Afroasiatic.... Hebrew belongs to the family of Afroasiatic languages commonly referred to as Semitic languages. The major division of this family is between East Semitic and West Semitic.... The Northwest Semitic languages comprise the Canaanite group and Aramaic.... A recent survey concludes that the Iron Age languages of Syria-Palestine are best viewed as a continuum having Phoenician as one of its poles and Aramaic as the other.... Hebrew is probably to be located near the center of this cline.... The Canaanite languages include Phoenician (which distinguishes the minority dialect of Byblos from the more widespread dialect of Tyre and Sidon), Hebrew (which distinguishes a northern dialect, probably centered in Samaria, from a southern, the dialect of Jerusalem and Judah), Ammonite, Moabite, and Edomite.
>
> The upheavals which rearranged the political geography of Syria-Palestine during the transition from [Late Bronze Age] II to Iron [Age] I (that is, about 1400–1200 B.C.E.) produced corresponding changes in the linguistic map. It is probably during this period that Hebrew can be said to have emerged as a distinct language (although the continuity of many earlier Northwest Semitic features must not be ignored).
> 
>Some poetic passages of the Hebrew Bible (e.g., Exodus 15; Judges 5) have been dated to this early period on the basis of certain archaic features of their language, but no extrabiblical text identifiable as Hebrew survives from this period....
> 
>The earliest written evidence of Hebrew comes from the archaeological period Iron IIB–C (800–586 B.C.E.). Hebrew must have existed as a spoken language earlier, and texts were undoubtedly composed in it; but none survives (beyond some archaic portions of the Hebrew Bible).[^7]

As also noted in the evidence appended to the question, the Paleo-Hebrew alphabet likely descends from the Proto-Sinaitic (which came from Egyptian symbols, not from Ugaritic, based particularly on discoveries made in the 20th century, especially in Wadi el-Hol). The Proto-Sinaitic script was likely in use between 1700–1400 B.C.[^2]

> The extrabiblical linguistic material from the Iron Age is primarily epigraphic, that is, texts written on hard materials (pottery, stones, walls, etc.).[^8]

The Phoenicians adopted the Proto-Sinaitic script by roughly 1000 B.C., as did the Hebrews (based on extant materials), which evolved into paleo-Hebrew. There were biblical manuscripts found at Qumran which were written in paleo-Hebrew.[^2] The Gezer calendar features prominently in related scholarship, albeit not without controversy.[^3] Interestingly, "Palaeo-Hebrew script survives until this day in the collateral branch known as the Samaritan script."[^6]

There was a shift from the paleo-Hebrew to the square "block script" during the exile (which was influenced by Aramaic, the *lingua franca* when the Jews were in exile). After the exile, the main transition appears to have occurred to adopt the square script and copy the biblical texts into this script (although some continued to be copied in the "old" / paleo-Hebrew script as well).

But based on extant biblical texts:

>... the earliest biblical texts were probably written in paleo-Hebrew script, though there are no actual extant Hebrew texts that predate about 800 B.C. (e.g., seal of Jeroboam II, c. 786–746 B.C., see fig. 3.2; Hezekiah’s tunnel inscription, c. 701 B.C.; silver amulets, c. mid-seventh century B.C.)—the earliest extant texts are written in this script.
> 
> The changeover from paleo-Hebrew to square (or Aramaic) script took place between the fifth and third centuries B.C. and would probably have been hastened by the Jewish exile in Babylon, where Aramaic was the common language....
>
> It is likely that the biblical texts were written on papyrus or leather scrolls. These materials were extremely perishable in the semi-arid land of Palestine and thus required constant copying by the priests or scribes. Jeremiah 36:2 gives some indication as to the writing process when God tells Jeremiah to “Take for yourself a scroll and write on it all the words that I have spoken to you.” Scrolls were limited in length by their bulk and manageability, but they continued to be used in synagogues even after the codex (a manuscript bound in book form) was introduced for private use in the second century A.D. ....
> 
> Hebrew manuscripts copied before the first century A.D. show two tendencies on the part of the scribes: they preserved the accuracy of the text, and at the same time were willing to revise or update the text.... At the same time the scribes were preserving the text, they also revised it in ... different ways ... [including that] sometime during this period the change from paleo-Hebrew to Assyrian square script occurred....[^4]

Concerning the scrolls identified at Qumran in the paleo-Hebrew script,

>Emanuel Tov suggests that the paleo-Hebrew texts from Qumran may derive from the Sadducees, since writing in this script was forbidden by the Pharisees.... He also observes that these scrolls display virtually no scribal intervention, and that the Qumran scribes may have been influenced by the Sadducean tradition of using paleo-Hebrew characters for writing divine names in biblical and nonbiblical texts to ensure that their sanctity would be recognized and thus not erased.[^5]


[^1]: "Some suggest only the Ten Commandments were written, while others think the stone inscription included the contents of at least Deuteronomy 5–26. Archeologists have discovered similar inscribed pillars or stelae six to eight feet long in the Middle East. And the Behistun Inscription in Iran is three times the length of Deuteronomy." Donald K. Campbell, "Joshua," in *The Bible Knowledge Commentary: An Exposition of the Scriptures*, ed. J. F. Walvoord and R. B. Zuck, vol. 1 (Wheaton, IL: Victor Books, 1985), 347.

[^2]: Michael S. Heiser, *OT281 How We Got the Old Testament*, Logos Mobile Education (Bellingham, WA: Lexham Press, 2014).

[^3]: *Cf. e.g.,* Koller, Aaron. "Ancient Hebrew מעצד and עצד in the Gezer Calendar." *Journal of Near Eastern Studies* 72, no. 2 (October 2013): 179–93. https://doi.org/10.1086/671444.

[^4]: Paul D. Wegner, *A Student’s Guide to Textual Criticism of the Bible: Its History, Methods & Results* (Downers Grove, IL: InterVarsity Press, 2006), 59–60, 62–64.

[^5]: James C. VanderKam and Peter W. Flint, *The Meaning of the Dead Sea Scrolls: Their Significance for Understanding the Bible, Judaism, Jesus, and Christianity*, 1st ed. (New York: HarperSanFrancisco, 2002), 152.

[^6]: Mark D. McLean, "Hebrew Scripts," in *The Anchor Yale Bible Dictionary*, ed. David Noel Freedman (New York: Doubleday, 1992), 96.

[^7]: Gene M. Schramm, "Languages: Hebrew," in *The Anchor Yale Bible Dictionary*, ed. David Noel Freedman (New York: Doubleday, 1992), 204–205.

[^8]: Bruce K. Waltke and Michael Patrick O’Connor, *An Introduction to Biblical Hebrew Syntax* (Winona Lake, IN: Eisenbrauns, 1990), 8.