Also I'm not quite sure how Super GIRL tarnishes Super MAN's thing as the Last SON of Krypton.
Dilution of concept. At one point in the Silver Age, there was Superman, Supergirl, a Super dog, a Super cat, a whole bottle city of miniature Kryptonians (Kandor), and if memory serves even a Super horse
. (and that's not counting all the villains in the Phantom Zone).
You forgot Beppo the Super-Monkey!
Although, to be fair, neither Streaky the Super-Cat nor Comet the Super-Horse were from Krypton. Streaky was an ordinary Earth cat who got powers after being exposed to kryponite (or something like that) while Comet was a former centaur who had been transformed into a Super-Horse by magic.