From china, to england and wales(flag), to portugal (sometimes included with the old coat of arms,) mayan ( seen eating its own tail,) china (seen in many celebrations,) greece, and many more, despite some of these cultures not having met in a noteable fashion until very recently?
Bad translations that shoehorn entirely different things under the same label. More can always be said on the matter, so if anyone would like to address the (mis)application of the term 'dragon', please feel free to do so! For the meantime, OP, here's u/itsallfolklore addressing the ostensible commonality of the dragon.