The chain that Adeline was wearing, the one with the dragon pendant, was in fact a magic object that Azriel had created around three hundred years ago. Its main purpose has always been to find the next ruler of Wyverndale.
During that time, humans were very much aware of the existence of Dragons. But there was enmity between the two races. Dragons would go to the nearby human settlements and soar down from the sky like rain. And they would wipe out the herd of domestic animals that the humans had raised with great care.
Likewise, the humans would often climb the hill and would enter the Dragon Crypts in order to kill the beasts. They would treat the Dragon Crypt as some kind of treasure hunting ground. And they would savagely kill the Dragons, Wyverns, and Wryms as though they were a part of an adventure quest.