Re: Rhinos -- Good lord. Yes, attributes have been constrained and it causes (especially in the case of Strength) some wonky discontinuities. We got it. I honestly don't know how this proves any grander point than giving all monsters stats and trying to fit all monsters into a scale mostly meant for human (or human-like) PCs causes some loss in granularity in modelling all creatures.
I think Beowulf is a good example of how the various characters we tend that influenced or we now try to put into the D&D model, well, vary. Some of them are powerful because they were born with it (/bathed in the fires of the gods, etc.). Some are not powerful because they are mere mortals. Some are mere mortals but get to do the IRL impossible. Myth and folklore (and modern fantasy) follow no one formula. For D&D to be able to fit all these stories even passably well, there probably needs to be more than one model of being 'a martial.'