No, see, what happens is simple. Every next movie we see the little girl all grown up and with their kid, who is in the spitting image of herself when she was younger. At that rate, between movies, it's been about six generations.

So, as you can clearly see, Ash not only doesn't age, but he is immortal.

It's nice that someone takes these recurring movie characters into account, their cameos are interesting… but about the "not aging" thing, that could be said about absolutely every single character in this anime series except Ash's Lapras.