So, for a long time, one of the arguments made to support the idea that Superman is the 'greatest superhero' in-universe, is the idea that he's the 'first superhero' who 'inspired' the heroic age. Pre-COIE, and in the New 52, he was literally the first hero (on Earth 2, and I guess, Earth 1 as well). Post-COIE, he was the first 'modern' hero after the JSA.
But did he really 'inspire' the emergence of other heroes and the start of the heroic age?
I mean, consider the other heroes usually presented as Superman's contemporaries in various continuities. Bruce Wayne had already spent his life training to be Batman. He would have become Batman irrespective of Superman's debut (I think in the New 52 timeline, he was around at least a few months before Superman first appeared). Barry Allen gaining his powers had nothing to do with Superman...his decision to put on a costume also had nothing to do with Superman. Hal Jordan being found by Abin Sur and becoming Green Lantern had nothing to do with Superman either. Nor did Diana coming to Man's World. Or Oliver Queen being trapped on an island, learning archery, and deciding to become Green Arrow.
Starting to get the picture?
I mean, its not like if Superman didn't exist, superheroes wouldn't exist. There are in fact several alternate reality stories (The Nail, Flashpoint etc.) which prove that. So exactly how did Superman inspire the heroic age?
At most, we can say that Superman served as the harbinger of the new era, from the public POV...but even so, that era was the product of several unrelated events that culminated in the sudden emergence of a number of 'superheroes' within a short span of time.
I understand the fact that Superman is the real-life inspiration for the entire superhero genre...but it really doesn't make sense in-universe where each character has his/her own origins and mythos completely unrelated to the Man of Steel.