[dsc]

“It is clear from a reading that Sahagun fully understood the Aztec god Tezcatlipoca’s similarity to Satan.”

Tezcatlipoca *was* Satan, but that’s not the point.

I was asking for a source for your assertion that the Spaniards didn’t regard the Indios as human.

[Natural Law]

It would probably take far more study than you appear willing to invest to discover or deduce the prevailing theological view of the new world people by the Conquistadors. However, in 1537 Pope Paul III issued a series of encyclicals declaring it heresy to describe Indians as other than human. Popes don't and didn't get involved in trivia or insignificant issues indicating the magnitude or prevalence of the problem.

Unfortunately, 1538 the pope's declarations were nullified by Spain's monarchy, which declared the pope's declaration in violation of the agreement between the monarchy and the Vatican concerning the powers of the monarchy in the Americas nd the official Spanish doctrine of a subhuman status of the indigenous peoples of the New World was further extended.