You're missing the point. The tribes did not hear about what was happening in Spain, they only knew of what was shown here. The laws were BS anyhow when you look at what happened AFTER that. They enslaved entire populations, numerous tribes and worked them death and then replaced them with Africans they imported to do the exact same thing to. Regardless of what laws they may have passed back home, that did not translate into better treatment for the people whose lands they invaded. It changed NOTHING, and this continued for generations. their attempt at " better treatment" was just a horse and pony show for their investors. Nothing more.
You should also consider that most of what Europeans think they know about the tribes, including the Aztecs was written by those who justified trying to exterminate them. No it was not " proven", far from it. Their interpretation of events was skewed by their own bias. From our understanding however, prior to the European invasion, Far fewer people wound up dead from Aztec wars than did so from European battles. The Aztecs actually preferred to take prisoners of war alive rather than actually kill them and gave their opposition a chance to surrender. Killing their enemies on the battlefield was seen as undesirable and without honor, unlike European/ Viking traditions of preferring to die in battle. The objective was to actually try to capture them alive instead. There is no word for " Sacrifice" in the Aztec language. Only some of the people from the actual battle were actually charged and killed for " war crimes" in the temple. This was considered more like executing criminals not "human sacrifice" as was invented by the Christians who attempted to demonize them.
You do not have "one story" about how the majority of tribes being peaceful, you have Hundreds from different sources, different tribes and even those Europeans who first encountered them. This wasn't "invented to make people look better", it was just the norm. Wars among tribes were a pretty big deal and rare when they happened and involved politics from numerous nations due to interrupting trade routes and tribes risked backlash from allies and trading partners of those they chose to war with. Those that chose to do so had to answer for doing so to other tribes, it was not an easy task for a tribe to choose to take that route and they risked much to do so and usually resulted in much hardship for themselves. I am not saying it didn't happen in any way, I am saying that it was far more complicated than most realize due to the understandings and agreements made between the many tribes on what was expected of them. They weren't just able to do so and not expected to answer for it.
Two things.
One. Regarding importation of African slave labor. If you look at the percentage of african descent people living in Latin America, you'd find the regions which were least populated with natives at the top - Brazil, Venezuela, Colombia. Those were also the regions where massive cash-crop plantations were set-up.
The west indies were thoroughly stripped of its native people by a combination of war, disease, famine and slavery. There are no native-americans in the west-indies.
This leads me to my conclusion - regions which were heavily populated by native-americans did not have a large quantity of african slave labor imported because it was heavily-populated. Despite the desolation in the century after Europeans reached the new world, the native populations in mexico and the peruvian mountain range bounced back. The lack of african slave labor was especially evident in the silver and gold mines in what is modern-day Bolivia and Peru - the altitude was so high, that slaves which were imported to work in the mines died because of it. They couldn't do slave-labor in 4Kmeters above sea level. This is why local natives were used as a form of slave labor, which was the mita system that they had adopted from the Incan Empire where subservient tribes paid "taxes" (or "tribute") with labor as a form of "national service". This is why regions around the mines are much poorer than others.
Regarding Mexico, the colonialist conquistadors employed the encomienda system in which they forced tribes into service.
Two. Regarding the Nahuatl religion, its depiction of ritualistic sacrifice and warlike state. Not unlike older Pagan faiths in the old world, which also employed human sacrifice (Roman vestal virgins, Norse blot, etc.), Inca and Nahuatl also included human sacrifice. Inca on a smaller scale though, which had ritualistic sacrifices of young virgin couples (children), as a symbolic significance for their faith in the sun and moon. Children were also sacrificed during hard times, and when the Incan king died. This is not too different from Moloch Baal worship by the Phoenicians, Egyptians burying a pharaoh with their slaves, and other nice things I probably forgot about. Oh, I think that in the old Slavic tradition, before the Norse united the tribes under the Ruriks, whenever a husband passed away and left his wives behind, one of his wife would kill herself at his burial site. I think it was usually the one that loved him the most.
Nahuatl on the other hand is interesting because it employed frequent raids and wars in an attempt to keep a steady supply of captives. Even if you look at the borders of the three-city coalition, with its tributary states - you'd see that they had deliberately left some cities as rivals so they could repeatedly raid them for captives.
There is a bunch of videos here, a good watch. Evidence is a mixture of Spanish sources and archaeological sites.
Where is your sauce for this claim you made -
"Only some of the people from the actual battle were actually charged and killed for " war crimes" in the temple. This was considered more like executing criminals not "human sacrifice" as was invented by the Christians who attempted to demonize them."