First of all, attempting to add some character depth by considering what dietary choices Diana might make connected to a formative experience from her youth =/= preaching. FFS. To me, it actually makes these characters more rounded out and interesting - they go through a process of decision making, just like - gasp! - REAL people!
As for Pocahontas and The Lion King being the "most thoughtful" Disney movies... I don't even know where to begin ripping on that. Pocahontas was othering, reductionist, simplistic and inaccurate. Many Native American people of Pocahontas' nationality were righteously pissed off with that movie.
The Lion King reinforced social hegemony - the "beautiful" people and the ones who could behave by their law and dictates were allowed to exist within society, wheras anyone else on the fringes (the skinny, lame Scar and the hyenas) were ostracized and considered worthless. How is that a good message to teach children? Especially as the characterization of the hyenas was also based on inaccurate stereotypes. And ESPECIALLY as it reflects our own screwed-up culture and the way we marginalize the disabled, mentally ill, "unattractive", etc, etc, etc, etc, etc...
Finally... you're basically equating two incredibly different continents and their people (America & Africa) and ways of life as the same thing. Yeah, ancient civilizations didn't all think/feel the same about everything, just FYI. They weren't all the same just because they're ancient and therefore outside of your experience. Don't forget that Native Americans are composed of many different nations, with their own languages, cultures and customs. The attitude towards the "circle of life" would've differed from tribe to tribe. It is offensive and racist to speak about them as though they are a single entity.
Furthermore, this ridiculous contempoary romanticization of the way ancient people viewed their NEED to hunt and the way they related to that and themselves as part of the infrastructure of their environment is absolutely a modern and invariably Western conceit, divorced from the reality of life where every day literally was a struggle for survival. It wasn't all peace-signs and spirituality, smoking incense and paying honor to the kill. It was about preserving the ecological balance so they could SURVIVE. And again - many, many different peoples had different philosophies, religion, rituals, beliefs and customs around this.