donāt forget that some of the legendary creatures they were describing were from other peopleās mythos which were passed down in the oral tradition for gods know how long. You know what existed in Eurasia right around the time we were domesticating wolves into dogs?
these beasties. For a long time, science had them down as going extinct 200 thousand years ago, but then we found some bones from 36 thousand years ago. Which, yāknow, is quite a difference. Since you can bet that any skeleton we find is not literally the last one of its kind to live, many creatures have date ranges unknowably far outside the evidence.
In South Asia there were cultures that described a man-beast/troll forrest giantĀ whoās knuckles dragged the ground, and everybody from the west was sure it was superstitious mumbo jumbo, but you know what used to live there?
And did you know that some of the earliest white colonizers of the Americas heard accounts that there were natives still alive who had seen and hunted and eaten a great hairy beast, shaggy like the buffalo but much bigger, with a long thin nose like a snake and two giant fangs⦠so, like, mammoths, you know? but they were totally discounted because europeans of the time were like, elephants live in Africa and arenāt hairy, you canāt fool us, pranksters!
Anyway, the point is between the early writing game of telephone description thing talked about by OP, and the discounting of native cultural accuracy, Iām pretty sure most legendary creatures are in fact real animals one way or anotherĀ