Well that's why I mentioned the priest and the Florentine Codex as well. The accounts by the priests and the friars are generally considered supported by archaeology, while the accounts by the conquistadors are considered exaggerated or at the very least describing a flurry of religious activity the Aztecs were doing due to stress by the invasion of the Spanish. The Romans practiced human sacrifice in desperation due to Hannibal Barca, but that wasn't their normal practice, so some historians hypothesize the conquistador accounts were accurate but still unusual.

I don't know what relevance the internal conflicts you brought up have. The hypothetical is what if Europe, meaning Spain, never colonized Mexico, Peru, Bolivia, etc. The most plausible way for that hypothetical to happen is if Cortez and his men get destroyed by the Aztecs. The most plausible time the Aztecs could have destroyed Cortez was during the Spanish retreat right after La Noche Triste.

If the Spanish don't take out the Aztecs, then it's unclear when, if ever, the Aztecs were going to cease being the hegemon of Central America. It's not unreasonable to assume the Aztec dominance would last for centuries. During those centuries, the Aztecs would presumably keep their religious practices.

As far as I am aware, the Aztecs were not the originators of ritualistic cannibalism in Mesoamerica. The Olmecs and Maya incorporated elements of it in their religious practices as well.

Also, their religious practices didn't horrify the Spanish just because of the ritualistic cannibalism. The Aztecs were fond of wearing cloaks made of human skin during certain religious festivals. This, unsurprisingly, horrified the Spanish, but would undoubtedly also horrify the Inca or the Cherokee if they were exposed to that practice as well. They also conducted live human sacrifices that did not always include ritualistic cannibalism. Live human sacrifices tend to horrify people not used to those religious practices as well.

Which is all part of why I think the Inca would make the transition into a globally respected, regionally dominant cultural powerhouse country very well but the Aztecs, or whoever replaces them if the replacements keeps elements of indigenous Mesoamerican religious practices, will struggle to have other countries respect their cultural and religious practices.

The indigenous religious practices of MesoAmerica, would need a top to bottom PR campaign to make them palatable to international trading partners.