Why has the casting for Superman always someone younger...even with fans???
Brandon Routh was like 25-26
Christopher Reeve 24-25
Even with Lois...
Kate Bosworth 22ish
Margot Kidder around 29 so that isn't bad.
These characters I thought were ment to be 30 something and the actors playing should be 30 something or older???...
Actually, the rule of thumb has long been that Clark is "about 30 years old", which means he became Superman in his early to mid 20's.
The example above of a very old Superman is a serious departure, and is really a one-shot thing. Don't believe it's even in continuity with the regular comics. Just sort of a "What If?" story.
For quite a while now (believe it still holds, although continuity was recently "tweaked") the story's been that Clark left home when he finished high school, and traveled the world for seven years, taking college courses online, before deciding to go home and find a way to use his powers in public.
This led of course to the creation of a "new" version of Clark (whose looks had changed quite a bit and people hadn't seen in years anyway), and Superman.
If he was 18 when he left home, this would place the creation of Superman when he was about 25.