Not quite accurate.
Supes #1 = First Superman comic, first DC superhero solo comic, first pin-up in comics.
Even more importantly, it was the first comic that was entirely devoted to a comic book character as opposed to a comic strip character. Prior to Superman 1, only characters with proven mass appeal like Tracy, Popeye and Little Orphan Annie had been given their own books and the material in them was strip reprints. The success of Superman 1 proved that a character whose origin was in orginal comic book material rather the newpaper strips could not only carry his own title, but sell out and require two extra printings. It was a turning point after which original comic books began to take off and the strip reprint books, which had previously dominated the market, began to decline.
The success of Superman 1, no doubt contributed to Martin Goodman's confidence in giving his new character Captain America his own title right from the get-go without trying him out in an anthology title first.
So as far my choice, if the Supes is a 1st printing....
If it's a 2nd printing, I'll take the Cap!
Jeff