And of course, there is no other plausible explanation for these images except that the Indians were familiar with living dinosaurs.
Likewise, the dragons and space monsters that my son loves to draw are irrefutable proof that he has encountered living examples of these creatures.
Have your son ever seen pictures of dragons? I'm willing to bet he has, and his drawings mimic what he has already seen. Have you ever seen a space monster? Has he? Doubtful, therefore his drawings cannot be corroborated as being factual in their basis (he used his imagination). Have paleontologists dug up many fossils and skeletons of these various species of dinosaurs? Do they in fact have a very good idea, if not definite knowledge, of the physical appearance of these animals? Since the answers to both of those questions is "yes," then we know those ancient drawings are in fact of real dinosaurs who we know for a fact once existed.
I think your argument needs work.