This is the retcon - that the "Starship Class" suggests there be a USS Starship. Why?
A retcon would be saying "Starship Class" meant something other than what it's original idea was.
Since you've pointed out there is no evidence to prove either way what it meant, again, how is it a retcon
And if you didn't notice before, it is my suggestion
that there is a USS Starship which is just my opinion.