People – Akkadian was a language spoken and written in the land (called for a time Akkad) between the Tigris and Euphrates, near where Avrohom Avinu came from originally.
The Torah (and archaeology for that matter) shows us that there were settled cities, culture, and kingdoms quite early on – when there were pretty much only nomadic tribes and a few walled towns in E’Y. Here’s a radical thought – Loshon Hakodesh was literally that – the language that holy men, like Avrohom Avinu, spoke. And he spoke the language of the people where he lived. As the family of Avrohom grew, so did the language it transplanted into the land of the K’nanim, with the geographic shifts (for example, words relating to seas and coasts, which Akkad didn’t have, being land-bound) and other words describing new phenomenon (much like the gemara uses words like traklin, pruzbul, achsanya, that didn’t come from Lashon Hakodesh or from Aramaic).
The written language we know as loshon hakodesh continues to evolve, all you need to do is look at the inscriptions on the rimon found in Yerushalayim from the Bayis rishon, then look at the dead sea scrolls (even within those, there is a range of slight differences over the 200 year period within which they were written – you can see a frum point of view on this from Professor Lawrence Shiffman) and then look at the cairo gnizah materials and then look at our modern writing – slow but clear changes in the writing, evolving, as all languages do. It doesn’t take anything away from the kedusha of what is written or spoken.