Interesting question! Unfortunately, it's rather difficult to answer. We have no surviving pre-Columbian census records. And as far as I know, the Spanish do not have early colonial records on something like this. And even if they did, their numbers would be skewed what with the smallpox and all. Fortunately, this is something that archaeology can answer fairly easily - it's called a mortality profile. It can be reconstructed by analyzing the skeletal remains of individuals buried in a given area to determine the age at death. Unfortunately, like many Postclassic cities, Tenochtitlan is buried under a modern city - which makes extensive archaeological research rather difficult.
We can however, see mortality profiles for Classic Period centers like Teotihuacan - located not far from Tenochtitlan. So with the caveat that things may have changed in the intervening 500 years, we can at least get an estimate for life expectancy in pre-Columbian urban centers. Luckily, such a study has been conducted at Teotihuacan's apartment compounds by Story (1985).
The result is that the life expectancy was, by modern standards, not very high. Life expectancy at birth tended to fluctuate between 17 and 19 years old. However, this number is exceptionally low due to a high infant mortality rate. A large number of people died before they were 1 year old, and an even larger number died before they were 15. If you lived to 15, your odds of reaching an older age were substantially higher. There are additional mortality spikes in the mid 30s and in the 50s.
Storey compares this to mortality profiles in contemporary European urban centers and finds that they tend to match fairly closely. So to answer your question, albeit 600 years earlier than the date you gave, people in pre-Columbian urban centers had similar life-expectancies to their counterparts in the Old World.