In the original timeline? Not quite. "X-Men Origins" features a 18 years old Scott/Cyclops. "Origins" is set inbetween 1979 and 1983. "X-Men" 1 is set in 2004. Cyclops looks younger in X1, isn't it? I guess so.
Said that, if you pretend that there are ONLY 2 timelines, then Jean Grey is born in 1967. In 2004 (X-Men 1), she was supposed to be 37.
The problem with this "Theory"/"Explanation" is completely obvious and right there in the films.
Take a look at Moira in : Apocalypse. Once you do, the entire thing gets pretty laughable.
Just let it be the goofy, nonsensical timeline that it is.
Trying to make a bunch of excuses for that your non-mutants are aging better than your mutants who are "supposedly" aging more slowly than humans doesn't change one bit of that it's a goofball timeline that they are trying pretend isn't a goofball timeline.
Not that big of a deal, but the idea that it makes any kind of sense is just silly.
I think it would make the most sense if the main story of Origins was set in the same year as Apocalypse, as both show Cyclops getting his powers activated for the first time (while they already were "on" in Origins, his teacher's reaction to his sunglasses shows that they're a new thing). He's basically the same age in both movies anyways. That would time stamp X1/X2 as being set around 1998, so make of that what you will.
(My main point is that Cyclops was born before the timeline changed, so only his life events could be affected by the change, not his age or any other factors.)
Where is that written? All we know is that it was in the "near future" and fifteen years after Wolverine lost his memories (as eventually depicted in Origins: Wolverine).
Where is all that written? Jean was never given a formal age, as I recall and the movies factually are only two timelines, irregardless of how messy they are.
Onscreen evidence disproved that a long time ago when Days of Future Past tied everything into one mega series. Whatever First Class was intended to be, it not that now (and a lot of the same people in creative control worked on both).
Doctor Strange: "You are the right person to replace Logan."
X-23: "I know there are people who disapprove... Guys on the Internet mainly."
(All-New Wolverine #4)
Good question. ORIGINS messed it up. Unfortunately...
Time stamps on satellite maps shown on-screen in X2 were marked "2002" or "2003". And that were taken some time before the events of X2, of course.
X1 and X2 happen in the same year. 2004.
In X3, Beast is reading a magazine time-stamped 2005. TLS is set 1 year after the events of X2. New President of USA, even.
Here we go.
The movies oddly address the time line, regarding how characters look and what their ages are. Nobody comments that everyone hasn't aged a day over 3 decades, that's why in my head canon when I see them I try to think of them as only years apart not decades. As well as after DOFP the settings become less plot relevant to the stories they're telling. Apocalypse could have been told in the 70's and nothing would have changed.
Doctor Strange: "You are the right person to replace Logan."
X-23: "I know there are people who disapprove... Guys on the Internet mainly."
(All-New Wolverine #4)
Be careful trying to figure out the Fox X-Men timelines will turn you into this
https://images.app.goo.gl/pGXyNGAJo8ozrj6G8