James Gasik
We don't talk about Pun-Pun
Ok, sure.I understand the point of a trade language, now show me how often in human history two parties came up with a new language in order to use that to talk to each other…
As to why other races would have a trade language and humans wouldn't, it's simple. Human civilization supposedly came around after all the older races did. So by the time they got up and trading, there would have been a lingua franca already established. And they'd learn it and use it of course.
But it wouldn't be the Human language in this case. And nothing explains why Humans and only Humans would abandon their language.
As for Tolkien, his world has a lot less species cluttering it up. You have Hobbits (do Hobbits even speak their own language?), Dwarves, Elves, and Humans. Goblins/Orcs/Trolls/Ents, but who trades with them? No Gnomes, Tabaxi, Centaurs, Goliaths, Plasmoids, Owlins, Harengon, Tortles, Githyanki, etc.. to see here!
And Dwarves and Elves did apparently trade in Middle-Earth, as stated in The Hobbit:
(Gandalf): Mithril! All folk desired it. It could be beaten like copper, and polished like glass; and the Dwarves could make of it a metal, light and yet harder than tempered steel. Its beauty was like to that of common silver, but the beauty of mithril did not tarnish or grow dim.
And let us not forget Bilbo's (and later Frodo's) legendary armor, found in The Lonely Mountain itself:
"a small coat of mail, wrought for some young elf-prince long ago. It was of silver-steel which the elves call mithril".