"Do you have a problem with characters that don't age?"
Yes, yes I freaking do, and I'm far from the only one. That's why a lot of people, myself included are happy that the people behind the Pokemon anime finally got rid of Ash Ketchum and replaced him with new protags in the new Scarlet and Violet Pokemon anime. Characters that don't age are boring, undergo very little to no character development (especially if they are still 10 after like over 20 years), lose more often than not, could easily be replace with the original book protags or original video game protags who are far better and more interesting than them. The Digimon anime is infinitely better than the Pokemon anime, it has new protags every season, its protags age and pass down the torch to a new set of protags and if they stick around to help the new protags once in a while they do not take the spotlight away from the new protag or overshadow them and they defeat a ton of bad guys in the long run (Red the protag of the original first gen Pokemon video game and the Digimon cartoon protags have defeat loads of bad guys whereas Ash Ketchum couldn't even defeat Team Rocket and never even face its boss and Red defeated Team Rocket single-handedly including their boss before passing down the torch to Gold).
A lot of people, myself included, are glad that Ash-Loser-Ketchum has finally been retired, a lot of the video game protags would make far better protags for the anime than the eternally 10-years-old, perpetually devoid of any character development and maturing, perpetually friendzoned, lost every league except one on accident after 17 years Ash Ketchum:
https://www.youtube.com/playlist?list=PLzG_3q50DuPmhYi24aFWKothJ5qe5wAvn
This is why I much prefer the fanfictions, the ones that don't have Ash in it, the ones with the video game protags, the ones where the characters age or are aged-up, get real jobs, go on dates/get married (have some kind of love life unlike the 10 year-old loser Ash who never grow up and never go on an actual date, there's one tiny little kiss on the mouth between him and Serena but they censored it and we weren't allowed to see much of it then she left forever and he never saw her again, he never grew uo and never had an actual love interest), have kids, teach their kids good values and support their's kids goals and dreams, help train the next generation of trainers, maybe go on a journey or a quest with a friend or loved one to learn more about themselves and the world, etc.
This looks better than the lame Ash anime, so let's hope that those new protags will be allowed to age and that there will be new ones every new season (this is why so many prefered the Digimon anime over the Pokemon anime, the Digimon is ever-changing and always refreshing whereas the Pokemon anime had perpetually unaging loser kid for a protag, never had new protags every new season, and had a sore loser protag who just kept sticking around instead of passing down the torch to the next generation):
We'll see where Horizons will lead...
The only characters that I'm okay with them not aging (and those characters are
NOT human) are characters who are IMMORTAL amd were created to be IMMORTAL from the beginning, like an angel or a demon or some similar immortal spirit being/supernatural being (like the angel Aziraphale and the demon Crowley from "Good Omens" who look like adults and look like they're in their late forties to early fifties anyway) because they were never meant to age and never aging is one of the characteristics of their SPECIES, not only do these beings not age, but some of them can also sometimes shape-shift and appear any age they want. Though it's just a physical appearance or a supernaturally made corporation and they are not actually that age. 'Cause some of those beings are MILLIONS OF YEARS OLD CELESTIALS AND PREDATE CREATION ITSELF, like Aziraphale and Crowley.
As Dizzi said:
"If there's like an explanation like, "the guy is IMMORTAL and can't age" then its ok but otherwise its so awkwards..."
And as bowsette said:
"Yes. In something like Pokemon where Ash seems to visibly
de-age as the franchise goes on then it bothers me. It definitely takes me out of the moment if a child characters spend multiple years staying super young or not adjusting their behavior at all."
And zettafleya is wrong about young kids may not have an interest in a protagonist older than they are, a lot of them want to see the protags age and grow up with them, a lot of kids left the Pokemon anime when they reached 12 or 13 because age didn't age and didn't go on dates and didn't show any sign or growing up and maturing with its audience of kids. Those kids much prefer the manga and the fanfics.
And as this guy pointed out, no little kid truly wants to be like Ash Ketchum and they are better than him because they evole their Pokemon and want the strongest, and most badass Pokemon (unike Ash and is rookie team of garbage mons) and they can defeat several leagues single-handedly in the video games whereas Ash lost all of the leagues he faced in the anime save one he won on accident after 17 years, Noble Absinthe is telling it like it is: