This was the dawn of comic book
Comic strips were very popular. Creators of Flash Gordon Tarzan and Lil Abner were famous wealthy with covers on Time Magazine… Everybody read them, adults and children, male and female.
Siegel and Shuster created Superman as a comic strip when they were nineteen before comic books ever existed.
The early Superman storres were repasting of the original comic strip they were Not done under a work for hire agreement.
Therefore early Superman was for all ages.
The first Batman story was based on a story from the Shadow. Pulps were for adults.
Please look at the following link to an article I wrote. See what the influences of Batman and Superman were and see if the words kids or children were ever mentioned.