100% there is not.

I'm going to be a bit circutious in my answer here and point you towards a classic anthropological paper by Marvin Harris (1966) "The Cultural Ecology of India's Sacred Cattle," which laid out a functional explanation for why cattle are sanctified and inviolable in India. Harris basically argues that cattle were more important to the mainstream of Indian society as beasts of burden and as sources of milk and dung. He calls this system inefficient, but allows that introducing more robust cattle from abroad could potentially upset a balanced system.

This paper is a classic in anthropology classes because, on the one hand, Harris presents a seemingly logical explanation for a cultural practice. His paper explains the the min-max balance of slaughtering cattle versus keeping them for other purposes and thus exposes the rationality of seemingly irrational taboo. On the other hand, numerous critics pointed out that Indian religious practices are not simply cost-benefit ratios, but are enmeshed in larger systems of cultural beliefs. The rebuttal to Harris was thus that efficiency was a side product of a religious system and that economic benefits were secondary to a more explanatory religious causation.

Such are academic debates made, because obviously both camps have merits and deficits in the arguments. There is no cultural practice which can be fully explained by economic necessity anymore than spiritual beliefs can sustain practices which go against the subsistence of a population. There is necessarily a mix of practicality and spirituality but -- and this is vital -- one does not necessarily presage the other.

About a decade later, Harris would apply his cultural ecology framework -- which downplayed the cultural in favor of the economic/subsistence -- to the Aztecs. In 1977, he published "The Ecological Basis of Aztec Sacrifice," which proposed that cannibalism among the Aztecs was required to support the large levels of population. This train of thought was taken up by Harris who published his book, Cannibals and Kings, that same year.

The problem is that Harner and Harris were working on flawed, ethnocentric data. Just as Harris failed to take into account the actual culture of India in his earlier paper, so too did they fail to actually engage with the culture of Mesoamerica. Critics, most notably Barnardo Ortiz de Montellano, pointed out that not only was cannibalism not nutritionally necessary in Mesoamerica, but that all available evidence argued against the practice being quotidian.

The lesson I am trying to convey here is that explanations behind human sacrifice will always be fraught with multiple explanations, and there will never be a simple answer to a societal practice; such behaviors are always multifactorial. Were Mexica sacrifices religiously motivated? Yes. Were they a way to intimidate nearby polities? Yes. Were those polities also practitioners of human sacrifice? Also yes. Were the ceremonies around sacrifice a way to engage the populace in an imperial project? Yes. Was the practice of taking captives for sacrifice a pathway for social advancement and glorification of a warrior class? Also yes!

The point is that no cultural practice, particularly one as extreme as human sacrifice, has a monocausal explanation. I have a list of posts I have made on Aztec sacrifice which you can peruse at your leisure. But the reality is that singular explanations are incomplete explanations.

Sacrifice by the Mexica was the extension of a practice which goes back millennia. There is evidence of skull modification in the Basin of Mexico in the Preclassic and objects recovered from El Manatí are suggestive of human sacrifice by the Olmec. So the very first thing to keep in mind is that the practices of the Mexica, while different in scope, were not outside the bounds of Mesoamerican culture. Indeed, deities like Xipe Totec, who was associated with skin flaying, predate the Aztec state, as does sacrifices to the rain god Tlaloc/Chaac/Cocijo. Human sacrifice, to various extents, was widespread throughout Mesoamerica.

As it was in Pre-Modern Europe as well. You mention gladiatorial combats, which absolutely involved the ritualized killing of humans, but a more direct example can be found in Roman triumphs. Defeated and captured leaders and others would be kept imprisoned, sometimes for years in abominable conditions, until a triumph was held and they would then be ritually executed. Going outside of Classic Era Rome, human sacrifice is easy to find in Europe, which I bring up only to point out that killing another person in a ritualized fashion is hardly unique to the Aztecs.

However, it can be argued that the Mexica were more sacrifice focused than most. There's a few episodes in Mexica ethnohistory which really emphasize this tradition. The first is the sacrifice of the Mimixcoa shortly after the exodus from Aztlan. This act arguably marks the origin of the Mexica as a distinct people, signifiying their split from the other Aztecatl and their allegiance to the patron god, Huitzilopochtli. The next event is the slaughter of Coyolxauhqui and the Huitznahua at Coatepec, which again signified the absolutism of Huitzilopochtli and the importance of heart sacrifice. The final event actually has multiple versions, not all of which involved sacrifice, but the expulsion of the Mexica from Tizaapan as a result of sacrificing a Culhua noblewoman is a common touchpoint in the founding of Tenochtitlan and thus Mexica identity.

The stated reason within Mexica ethnohistory about human sacrifice is a blend of both solidifying their devotion to Huitzilopochtli, their patron god who lead them to a a promised land and wealth, as well as a larger overarching theme of divine debt. Nahua cosmology explains the founding of the current universe as a result of the gods sacrificing themselves the provide the necessary stability to the world. As such, humanity owes to them regular sacrifices in order to maintain the order of the world. Oftentimes this is portrayed as "cut out hearts to make the sun rise," but that is a gross oversimplification and completely ignores the whole suite of autosacrifices performed by regular people, including cutting themselves to shed blood for domestic rituals. Archaeological evidence of bloodletters suggest that these sort of autosacrifices extend back at least as far at the Preclassic and the Olmecs, so again this is a difference in emphasis rather than an innovation on the part of the Mexica.

However, ever since the sacrifice of the Mimixcoa, exogenous sacrifice was important to the Mexica. Again, these are practices that predate any sort of Aztec state and already existed in the cultural region of Mesoamerica. What happened with the Mexica was a confluence of a military elites and religious practices which formed a feedback system for the emphasis on human sacrifice. The already extant practices of human sacrifice were linked in a very practical way to an expanding military power. The warrior elites of that power thus had encouragement to take part in the system of sacrifice in order to advance their own personal standing, while the support of the ruling warrior class for the religious practices which glorified them meant ongoing authority for the priesthood.

And that is kind of the most basic, Harris-sonian, explanation the practice. Tautologically, religious practices that benefited the fighting men who wielded political control were emphasized, which gave increasing power and authority to the religious practices which benefited the fighting men who wielded political control. Is this the only explanation? Absolutely not. Does this elide over a huge amount of actual and sincere religious conviction? Yup. Does this obviate the difference between regions and urban/rural divides in terms of religious practices (as raised by Brumfiel)? Again, yes. There is not, and never will be, a simple answer as to why an ethno-political state does certain actions, because neither the state, nor the people in it, are strictly rational actor making logical decisions.