In the early days of comics - dribbling into the middle days of comics when I was more active in the industry - the quality of paper was low and the color palette available was limited. In fact, until the late Seventies, comic book colorists were pretty much making coloring suggestions rather than doing any actual coloring.

Color was transferred from a colorist's work by transcribers with wide interpretive latitude, through a bizarre technical process in which these transcribers would actually color four versions of the same page - only in red.

That is, one version of the page would have red colored into all the shapes where the colorist suggested a color that included blue. Another would be a page colored red wherever a color containing yellow appeared. And so forth. These pages were photostated successively, with the eventual product coming out in approximately the pattern the colorist suggested. This was never very effective, and severely limited the colors available. And then the low cost pulp stock invariably bled colors and lines.

So there were few options available when determining the hair and eye color of a main character who was supposed to reflect an Anglo-Saxon ideal. Superman, Batman and Wonder Woman all had black (actually dark blue) hair and blue eyes. Barry Allen's hair was yellow and no one is quite sure what color his eyes were. Batman is the only one of these characters whose origins actually suggest this ethnic ideal. Superman is an alien and probably should have something eccentric about his physicality besides the super-powers. Wonder Woman is Greek/North African and should probably look kind of Sicilian at the very least.