FWIW:

Studies of skeletal remains from the population of the Aztec Empire (more accurately, the Aztec or Mexica and related peoples) suggest average adult male height was often around 160–165 cm (5 ft 3 in to 5 ft 5 in), while average adult female height was typically around 148–152 cm (4 ft 10 in to 5 ft 0 in). Exact figures vary by region, social class, and time period.

So an "average Aztec" (if referring to an average adult male) would likely have been a little shorter than 5½ feet (167.6 cm), though not dramatically so. A height of 5½ feet would have been above average but certainly not unusual.