Nope, it doesn't. Fair number of superhumans all through history and prehistory. Big increase in (visible, the Eternals were always around) numbers during WWII. Maybe fewer public ones during the 50s, 60s, etc., but there were still some such as the First Line. Then boost in numbers again following the debut of the FF.
But how much of these fluctuations is the actual number of superhumans, and how much is a factor of how many of them opt to go public as costumed adventurers or menaces as a cultural thing, is kind of up in the air.