[@Ignis Sanat] Feel free to PM me if you wish to discuss your character in private!

[@Chiro] There's no upper age limit. Metahumans started emerging in the year 2000, so roughly 21 years ago. For the first five or six years, their powers were very minor and were mostly harmless, viewed with more amusement than fear by the general populace. Starting around 2007, however, metahumans with actually dangerous powers started appearing--some of whom decided to use them to commit crimes. This public opinion to shift drastically against the growing Metahuman population for a time, leading to a registration act being passed through congress.

This changed slightly when other Metahumans began intervening against the criminals sullying their communities names, though since both sides tended to wear ski masks and other common criminal methods of hiding their identities, it was rather difficult for civilians (and the police) to tell the difference between them.

It was only when the Champion (our Superman) appeared in his distinctly heroic-looking costume that public opinion began to shift back towards the Metahumans as they followed in his stead, adopting a more distinguishing appearance. Long story short, the Registration Act was eventually repealed when the Justice League helped to keep the Blackthorn Coven from taking over all of North America.

As for Mystery Men, yes. There were Mystery Men-type heroes starting with the Great Depression, all the way into the early 1960s. They didn't have superpowers, and were more akin to the Watchmen (minus Dr. Manhattan). By far the most famous of them was the group of six known as "The Impossibles", lead by the "The Wraith" (basically The Shadow). They were unfortunately (yet understandably) suppressed by the government in the 1960s after one of the former Impossibles became President, and nearly started a full scale nuclear war by dropping the bomb on North Vietnam.

So, from the mid-60s onward, it was technically illegal to be a Mystery Man, though after dangerous Metahumans and the Blackthorn Coven emerged, people kind of forgot about that.