Now, could we stick to the question of what evidence there is for Hebrew as a linguistically isolated language—that is, more isolated than any other language in antiquity (eg. Phoenician, Ugaritic, Aramaic, etc.).
I didn’t know you wanted a comparative, but even there an argument can be made that Hebrew was more linguistically isolated by reference to the populations who spoke the listed languages.
Ugararit — port and trading city where people came from different countries, cultures and languages for trade.
Phoenicia — a group of ports known also for their sailors, with repeated contact with different peoples and languages for trade, diplomacy, etc.
Aramaic — (according to what I was taught) was a lingua franca for much of the Levant for centuries, even centuries before the Babylon of Nebuchadnezzar and for centuries afterward as well. As a lingua franca, educated people from several languages would learn it, and it would be in contact with all those languages.
Hebrew — most of its speakers were farmers, shepherds or small craftsmen, plying their trade locally. Even most of their traders were really peddlers, never needing to know more than Hebrew. As a result, most of the population never even heard a foreign language, let alone learned one.
Based on the above, which of the languages would you say is the most linguistically isolated?