Yeah, JSA existed on Earth 2, and JLA was on Earth 1. It was essentially DC's way of expaining where the golden age heroes like Jay and Alan Scott went, when the new guys took over.
They each had their own Superman, though.
I'm assuming there's only one Superman in the tv series, which is cool. I was simply making the observation that DC used to push Superman as being the "prototype" super hero who inspired an entire line of heroes, and that this happened on every Earth.
But that trends kind of changed a bit... He's still important, but it wasn't Superman who was central to DC's reboot. It was Barry Allen.