As on today I've seen many superhero , supervillain films, Serials, comics, books etc.
And I found that every context contain one last thing is common that is FAMILY.
From Spiderman to Flash, from Avengers to X-Men all having that single common thing is either they need to protect their family after got enlightenment (साक्षात्कार) or they got enlightenment to protecting FAMILY.
Also Villain find out various ways but lastly FAMILY is the only key to survive their encounter with Hero.
My belief is that it was the cultural development that people look for miracles . They don't know the effect of gamma rays or krypton but they really think about Hero's.
Yes also Hero's family really do scarifies for them. They believe to avoid identity is better than recognition .
Now Moving towards we are going to Hero's identity , eligibility etc.
1) Hero should have dumb nature in their own original identity
2) They must have something abnormal with them.
3)They have some past which is to be avoid in public or in family also .
4)Also they got connected to villain by some of the story in past or may be family person.
Hero's are born (means they got enlightenment) for some specific tasks & they must have one coach with them or else collogue which are giving presence of mind .
Yes Although Hero owe their own time at the war but in general they must have team which is called as backup always.
Lastly Normal people don't expect to be Hero but they really love Hero's life .