I'm thinking of Tolkien's own statement that he was "in fact a Hobbit in all but size." His earliest experiences of the West Midlands, which he undoubtedly drew upon in his depiction of hobbits and the Shire, began as early as 1895 when his family moved to Birmingham and then to Sarehole in 1896, but I think of him primarily as a man of the 20th century. I think Edwardian is right on the money, but late Victorian seems appropriate too.
They are definitely of the race of Men, as opposed to Dwarves or Elves.
I'm not sure what you'd call young, but in The Hobbit, Bilbo at "about fifty years old or so" is described as "grown up".
Technically don't playable gnomes slip into Mystara due to Top Balista? I don't think said flying mechanical city ever showed up again, but the implication I got was that it was wherever you wanted it to be in there.
Why can't you just use them as is?
It gets a little weird when you start including Gazetteer and Dragon Mag articles into the mix. Orcs and gnomes did get PC stats, but they were primarily viewed as "monsters" first and foremost. Gnomes are listed next to gremlins and sphinx, orcs alongside other evil humanoids (goblins and ogres).
It'll be underpowered or overpowered depending on how you do it.
Ah, see I'm happy just fixing what doesn't work for me myself, and would be fine with using 5.0 as a basis for that. I don't take WotC's design work as gospel.
The Creature Crucible 3 are their own weird little segment because, sure, you got sphinges in there, but just the same you've also got downright regular re-occurring ones like Pixies and Centaurs from Tall Tales, and Aquatic Elves and Tritons from Sea Peoples which, I reckon most people would agree they don't really count on the monster side
