P.I., you're confusing ORIGINAL CONCEPT with FIRST ISSUE.
The concept of Hulk doesn't rule out the addition of other Gamma Powered beings like She-Hulk, Leader and Leonard Samson in any way, just like the concept Captain Mar-Vel doesn't rule out others using the Nega Bands.
The original concept of Superman, that of last survivor of Krypton, rules out adding OTHER Kryptonians to it.
And Superboy contradicts the fact that no one knew who Superman was when he arrived on Metropolis in Action Comics #1...
