The "Max Village Population" figure on the Stats screen is the highest number of villagers that you've ever had in your village. It does not represent a population limit. The population limit is determined by available housing. As long as you have a villager who has skill at building (and construction is set as their preferred skill) your tribe will take care of constructing new huts as they are needed. Your villagers can build a total of 3 new huts (Puzzles 1, 3, and 6), which will allow your population to grow to the maximum allowed for your device (65 villagers on most devices).