This assumes we have all the knowledge back to the origin of humanity, which we don't. Some have even asked if Hebrew was the original language, though the term Hebrew is first known well into what is considered the Historical period of human existence, only about 3500 to 4000 years ago. And the speech we know by that name is clearly a variation of a form of old Phoenician or Canaanite speech.
Old Semitic
We know the original alphabet used by the language form we know as ancient Hebrew was written in a form of Old Phoenician script, similar to the variation used in south Arabian. The Hebrew examples we have in historical or biblical documents are almost entirely in a script developed in the Babylonian Exile, but two of the thousands of documents found at Qumran in 1948 were in the Old Hebrew script, a version of old Phoenician writing. These were not biblical documents. (See authorities on the Qumran scrolls for details.)
Here are some perspectives that may provide more background clarification. I write as an anthropological linguist and an ordained Baptist minister. My wife and I spent 36 years as missionaries, mostly in Africa. Details are reflected in various articles on my websites.
No Torah Comment
The question of the first single language is not addressed by the Torah or New Testament. It is the kind of theoretical question representative of analytical modern thought, a different and comparatively recent worldview in human history.
It does not seem to be a question of focus for the Scriptures. The abstract question of the original human language is speculative at best. If that had been a meaningful question in that era, I would have expected the question to be specifically addressed in the Hebrew Scriptures.
It is not. Thus we do not expect the ancient writings to answer modern questions that arise for us only in our context.
Comparative Linguistics
Considerable knowledge has been discovered int eh last few decades that have given us great insight in to the history of our race interms of language nad cultural development. These findings throw light and provide context for interpreting ancient texts like those of the Bible.
If we take the modern approach and assume everything is about us. if we just insist on wrestling the ancient texts into submission to our expectation, we do violence to the text, scripture or whatever ancient texts. We must honor the integrity of the text.
The question of the original language is a technical question. Recent historical attempts to investigate that question have led to the that family of sciences known as Linguistics. Comparative linguistics specifically tries to find universal forms of structure, sound sequence, tone, intonation, and other language features that will account for current known speech forms and the relationship between current speech forms.
Exciting Scenarios
Comparative linguistic evidence has not found enough evidence to account for all the various language families in a single source that will explain all the variations of phonetics, structure and vocabulary or the worldviews represented. ut exciting scenarios development in our discovery of the movement of peoles and development of Empires and the languages they used for administration.
Hebrew is closely related to one group of historical and current human speech forms that have not been related yet to other families. The broadest structure in the comparative language tree of related forms of speech is the Afro-Asiatic language group, in which Hebrew is a comparatively young version, going by comparison of characteristics with other similar languages.
Languages and Peoples
Definitive information on the relationship between the various languages and language families of the world is available online in the Ethnologue, published by the SIL International, also operating in cooperaton with Wycliffe Bible Translators.
The Ethnologue is the repository of the code system and definition of languages of the world known as the ISO Code system for world languages. This codeset is also known as the Registry of Languages.
For 7 years I was the Editor of the sister Codeset for Peoples of the World, the Registry of Peoples. You can find information on these codesets and the related registry codesets in the Harvest Information Systems, managed by a consortium of key world mission agencies and cultural-linguistic research groups, from thousands of field teams, universities, and research and strategy agencies around the world.
For exciting portraits of the setting in Palestine, Mesopotamia and the Roman Empire in the first century before and after the birth of Christ, see these articles on my website:
First-Century Language in Palestine and the Roman Empire: With Addendum on New Testament Texts
Greek and Aramaic Among 1st Century Jews
Hebrew – The Original Language? (Of Course Not!)
Languages Jesus Used
Literacy Training in the First Century
Orality and Literacy in the First Century
Textual Themes and Language Variations in the late Prophets
See further resources on Internet sources:
Will the Middle East’s Aramaic language survive?
The Mandeans - the last remaining Gnostic organized church
Initial notes written in an email exchange 28 February 2014
Developed October 2016, October 2017 and January 2018
Posted on this blog 20 January 2018