The First Language
There is a very interesting article in the latest Biblical Archaeology Review about the evolution of the Hebrew language and its treatment as a holy language. On its most general level, How Hebrew Became a Holy Language by Jan Joosten is a nice summary of how languages evolve, which can be very useful if your adventurers delve into ancient ruins with ancient inscriptions, or, Tarzan-like, meet up with ancient lost civilizations.
Subtle changes in the meaning of words and subtle changes in the use of grammatical constructions altered [Hebrew’s] nature… A phenomenon that illustrates this evolution can be found when words with a general meaning came to be used exclusively to designate specific religious items or concepts. For example, take the Hebrew word torah. In most of the Biblical books, torah simply means “teaching,” or “direction.” In the late books of the Bible, however, torah takes on a different meaning. It now refers to the book in which Jewish law is written down.
This is an obvious way of laying down red herrings or wild goose chases for the player characters to follow. Interestingly, a similar process happened to the word “bible”. The term (as biblia) originally meant any collection of scrolls and later books; the term biblia sacra meant “holy books” and was brought into French as just “Bible” from whence it was brought to English. But nowadays, “bible” can also mean any authoritative work. That might be an interesting evolution for any sacred object in your game. A non-player character tradesman might well describe an extremely-well-made tool as the excalibur of their profession.
Hebrew also, of course, borrowed words during their many tribulations:
The Book of Ezekiel contains dozens of loanwords from Babylonian; Exilic and post-Exilic books of the Bible evidence a high proportion of Aramaic loanwords. The latest Biblical books attest around 20 words borrowed from Persian.
One of the ways that words get borrowed is through similarity, changing the meaning of existing words in the language (Hebrew, in this case) due to a similarity with words of nearby cultures:
A nice example is the Hebrew word yomam, which in classical Hebrew is an adverb, “by day,” but in Nehemiah 9:19 is used to mean “day-time.” The earlier meaning was forgotten, and the later meaning arose on the basis of a similar-sounding words in Aramaic.
Something really interesting in the article, from a fantasy perspective, is that for centuries many people believed that Hebrew was the first language of mankind, the language used by Adam, Eve, and God in the Garden of Eden. The Bible certainly seems to imply a universal language before the Tower of Babel.
The idea of a real mother tongue is controversial in modern linguistics, but it’s pure gold in fantasy. The Norse and other notion of true names implies a True Language in which those names exist. John Dee proposed a celestial speech, later called Enochian because Enoch was the last human to know it.
In modern fantasy, Ursula K. Le Guin used the Old Speech in her Earthsea stories; it was the language used to create the world. Neal Stephenson used the idea in Snow Crash that there is a language uniquely attuned to the human mind and able to program it, much like computer languages are used to program computers.
I used a similar idea for the tablets of Enki in The Road. The Tablets provide extra-special knowledge and skill in whatever their topic is (language, war, etc.) because they were gifted by the gods to the first City of Man, to teach mankind the great crafts of civilization.
And of course, bringing it back full circle, the tablets of Enki are loosely based on the stories of Prometheus and Ishtar, but heavily based on Moses and the tablets of the law.