The song very clearly says, “The Professor AND Mary Ann”.
The Ginger was Howell’s side piece. His wife didn’t mind as long as the credit cards worked. The Skipper had his ‘Li’l Buddy’.
A lot of the sitcoms of that era had subtle (or not so subtle) homosexual subtexts.
If they reboot Gilligan’s Island, the Skipper would be a pedo, Gillian would be a 16 yo boy, The millionaire would be a nerd, his wife would be a trans, the Movie star would be a global warming activist, the Professor would be a LIBERAL anti American and Mary Ann would be cast as a Conservative nut case..
In the first season (filmed in glorious black and white) it was "and the rest". Season two or maybe three the Prof and America's Sweetie got their recognition.