I mean, if you've got Scalekin on the First that look like dragons, act like dragons, and do pretty most of the things that a dragon does, you CAN call it a dragon.
You can also call a dolphin a fish. It's shaped like a fish, it swims like a fish, it eats fish like a fish. But if you call it a fish, you're still wrong, for a variety of biological reasons. The same goes for dragons on the source compared to "dragons" on the First.
In the world of FFXIV, the category of creatures known as "dragons" are defined as lizard-like aliens living among us (or descendants of lizard-like aliens living among us). There may be other creatures, voidkin or scalekin who LOOK like dragons, but they are still voidkin or scalekin, not dragons. There will very likely be dragon-like creatures on the First, but aside from some that may have tagged along with the Crystal Tower, they will not be true dragons - just dragon-like scalekin and voidkin. They will likely not be nigh-immortal, for instance, and they will likely not reproduce asexually as true dragons do.
Of course, for all the locals are concerned, they might as well be true dragons, since they are the only dragon-like creatures they will have ever seen!
