Yes, you can theorize on a non-human point of view, with reasonable accuracy if you're familiar enough with the creature in question. The best example for me is pet cats. Once you've had a pet cat for a number of years, you get to know their point of view pretty well. You can usually tell what they are trying to tell you, when they're frustrated, and so forth. As well as the differences in points of views among the different pet cats you have. Of my parents' three cats, two of them have very different points of view of the third one. Some of the cats' concepts may be uncommon in modern-day human society, such as territoriality, but they can be understood if you know the cats well enough.
It is true that you can't know
exactly how the cats are thinking. But a lot of the time, you can get a reasonably good idea. It's also true that I can't always know what my best friends are thinking. That doesn't mean I can't in general understand their point of view, though. And I'm not actually sure I understand my best friends' points of view as often as I understand my parents' cats' points of view!
Perfection also brings up good examples in post 19. I don't think it's fundamentally different when considering non-human animals. Although I can see it differing by animals. It's probably much more difficult to theorize upon a coral's point of view than a cat's.