The Beorn people who first settled The Burgue took their name from their native word for "Bear," which is why a bear flag still flies over the city.
In the lore of the series, Gloamingside is said to have acquired its new moniker 'Carnival Row' from the literal carnivals that filled its streets when the first fae moved into the neighborhood from far-flung Tirnanoc.
To design humanistic creatures the audience could root for, the makeup and costume departments were tasked with creating creature designs that were both high fantasy and also human in a way that worked in extended dramatic dialogue scenes.
In the world of "Carnival Row," the continent of Ignota is home to a variety of races that include faun, trow, naga, raksha, and mouros. Largely unexplored, Ignota is where faun (aka pucks) and their empires are located.
Travis Beacham wrote the original screenplay for "Carnival Row," mainly for himself. He didn't think it was a script he could sell, but it turned out to be the piece of writing that launched his career.