Marvel comic timeline is meant to move at something like a third of real time, so despite being 60 years in the running only 20 years has passed for many characters.

Except Spider-Man who has been reset more than most a few times.

And many of the X-Men characters since they can currently resurrect into bodies aged to their "prime".

Or anyone who spent time in another dimension or timeline as was the case with the Fantastic Four and Cable respectively. This is how they aged up Franklin Richards very recently a few years ago from a tween to the 16/17/18 or so he is now even though he was a toddler back on the mid 80s when hanging out with other actual kid superheros such as The Power Pack.

Problem with Spider-Man however is several upper management overruling many writers and continually resetting Peter back to bachelor status so he can dally with MJ, Felicia, a new writer's OC self insert, or whatever. So he's more screwed up than most despite never properly spending any time outside the 616 timeline as many others have.