I'm running a campaign set in Chult. In making sure I know the setting well, I came across this entry on the Forgotten Realms wiki, which notes This article is about the tribe of Chultan humans. For the race of humanoid felinids, see Tabaxi., and goes on to explain:
"Tabaxi" was also a term given to a race of humanoid jaguars found in both Chult and Maztica. It has been suggested that this was an error in naming. The explanation was that an explorer from Cormyr saw a Tabaxi tribesman dressed in ceremonial garb of panther skin and was told by a guide that the man was a Tabaxi. Misunderstanding what the guide meant, this explorer assumed that all cat-men were called "Tabaxi".
In actuality the Cormyrean explorer was not far off from the truth. The human tribesmen named their people after the enigmatic feline-humanoids.
This is also covered in Who was this character from the Tomb of Annihilation adventure before they became a monster?, which references Dragon+ magazine article which appears to confirm some of this, at least as far as metagame history goes.
But, the actual in-print 5E book covering Chult, the Tomb of Annihilation adventure, doesn't mention this at all. Instead, the human natives are referred to as "Chultans", and the only references to "Tabaxi" are to the feline kind:
Tabaxi are feline humanoids, originally native to the western continent of Maztica. Some Chultans refer to them as “cat folk” or “leopard people.” Groups of tabaxi wound up in Chult after escaping from slavers. They are a cultured people and seldom evil. A few work as guides out of Port Nyanzaru. Others enter the jungle in small groups to hunt grungs and goblins for their own purposes.
Sooooo, what's the story here? Are what were the "Tabaxi people" now Chultans?