I wouldn't go so far to rank those. Unless we get rivals for those (which I don't think we will ever get) these titles were given to those individuals after they had reached top levels. Sailing those seas, I would never draw clear lines of superiority or inferiority. Every battle between members of that class would last for days with an outcome that strongly depended on the situation (one quick wrong decision, an external element distracting one of them, etc.). Meaning the fight, if repeated over and over, could still go either way again - and again only after a 10 day long fight.
I start to think that at this point we have to understand those titles were created because of those top level people.
"Oh look, that's Kaido. He's unrivaled, a literal monster in all terms. (And since he's not really human but rather some weird creature/oni) let's name that guy Strongest Creature of the World.
Same for Mihawk."Oh look, that's the swordsman that fucked up everyone who ever dared to face him. He must be the Strongest Swordsman on the World."
Same for WB. "Oh, look. That's Whitebeard. Just a regular human guy but he's literally fighting the Pirate King/ or superstar pirate Gold Roger (depending on the time) on equal terms. He must be The Strongest Human on the World."
Surely Roger had some title too, prior to his ascension to PK. Surely Shanks has some title, too. One that isn't any less worth than WSS, WSM, WSC, etc.
In one piece, titles don't make people. People make titles.