Rashi to B'reshis 2:23 says that the language Adam spoke was one that Rashi calls לשון הקדש, lashon hakodesh (or l'shon hakodesh), and that contains the words אִשָּׁה and אִישׁ. Keeping to Rashi's nomenclature but abbreviating, I'll here call it lhk. The Tora is written in lhk, as evidenced by the words אִשָּׁה and אִישׁ appearing in it. (That doesn't prove all the Tora is in lhk. But presumably large swaths of it are.) Moreover, Rashi (same place) says the world was created with, or in, or by means of, lhk.
This implies that lhk is the oldest language in the world.
Yet linguists will tell you that the language the Tora is in has ancestors, including Proto-Semitic and Proto-Afro-Asiatic. Of course these are dead, so that doesn't quite contradict anything above. But linguists will say further that these languages predated the language the Tora is in. That seems definitely to contradict the above.
According to Rashi, do we simply disbelieve the linguists? Or is there some way to reconcile Rashi with them?
And do other rishonim disagree with Rashi in such a way as to be more linguist-friendly? What do they hold?