There are pros and cons for either demographic: whilst being older may be ideal since not only you bypass age restrictions, you also have the capability on purchasing it with your own money without having to ask parents for that given that you have employment and recurring income. Gaming as a kid gives more time without having to dwell much on responsibilities that adults have to worry about but at the same time are held by school.
I remember Cyberpunk 2077 sucking me into its world, I sometimes walked slowly through the streets taking in sights and sounds.
I had that all the time as a kid, Monkey Island, Betrayal at Krondor, you name it. For children, like you said, everything is new and a fantastic experience, give it enough years and it becomes not stale, but normal.
Now, many years later it has become rare. But when it happens it’s awesome again.
That’s also my reason for not being excited over GTA 6. It will never live up to feeling of 3, Vice City or San Andreas, even 4. Those times are over for me. 5 was fun, but nothing special anymore.