It was Mayans in the movie. They indulged in human sacrifice and probably cannibalism also but the Aztecs were at the apex of that system.
Good point — those ziggurat temples are Mayan, not Aztec. Yet they’re behaving like Aztecs, and the timeframe would seem to make them Aztecs. I hadn’t thought about it before but I’m now realizing the movie has its history kind of jumbled up.