I've had the game on my tablet since it came out. I've neglected the game, and have gone through probably six or seven mayors. However, the townspeople have been the same the whole time? Os it just my game?

No, it's not just your game. Only the mayor (and the adopted child) age. I don't adopt, I just wait until my mayor retires then the game let's me pick a new one like at the very beginning except they 'inherit' the old mayor's house, tools, clothes, etc.

But it's not just your game.