How can one look at an ancient work of art and determine whether the animal depicted is real or mythical-imaginary? You seem to be implying that there is a difference such that the Ica stones would indicate whether the animal drawn was real or imagined. I don't follow your reasoning here.
So how do you know which of those two alternatives applied to the culture which produced the Ica stones in question? (By the way, I didn't call it an ancient culture because it is not at all evident at this point that they are ancient.)
Lastly, I thought I saw where you asked what paleontologists have to say about the accuracy of the Ica stone drawings in terms of depicting dinosaurs accurately. I hadn't brought up that topic because I don't have immediately at hand a citation. But because you've asked, I'll mention an article I read a few years ago that was written by a paleontologist (technically, a comparative anatomy professor specializing in vertebrates). The article discussed several such art works, including the famous Cambodian engravings (the alleged stegosaurus) as well as the Ica stones. The paleontologist said that if the depictions were meant to look like dinosaurs, they showed various fundamental errors. Yet, I actually don't consider that particularly important because even if they depicted real animals, both ancient and modern artists sometimes work from the reports of others and not a "model" sitting quietly in front of them.
As written previously, the Ica stones have plenty of other problems which are far more serious, such as dating measurements and provenance. It is very difficult to take the stones seriously until provenance issues are addressed, especially when we know that most of them are admitted forgeries/hoaxes. (In impoverished areas, forgeries of these sorts are not entirely rare. Consider the famous Paluxy River Tracks of the Depression Era.)
This has been an interesting topic. It is a good illustration of how scholars go about weighing such evidence and determining likely origins.