I cant find any detailed data of the creatures. Is there anyway to get details like health/lvl range, zone etc from the wow classic API??
As far as I know, the Blizzard API has virtually zero information on each in-game mob. As I understand it, the data available is limited to pets, mounts, and hunter tameable creatures.
I learned this on this forum, in a post that is now years old. Because it is years old, it might be out of date, but I too have tinkered in the endpoints, as recently as this week. Based on the lackluster API documentation and endpoints, there does not at all seem to be a documented endpoint for data on a specific mob.
If you are looking for something similar to the Wowhead data, that is an entirely different dataset not at all connected to the Blizzard WoW API. Their data comes from an addon that collects information and sends it back to Wowhead for display on their website.
As far as I know there is no API for the Wowhead dataset.