WSS > swordsman. Right. You try being WSS in real life and win against a sniper using a laserbeam and making genkidama bombs without touching.
Haki is under swordsmanship...right. Tell that to Strongest Sandalman Luffy whose CoC is 2 levels higher than WSS candidate Zoro. You are the one who keeps attacking with high powerscaling spirit as if you make manga rules, don't get frustrated yourself.
The difference between Shanks and Lufffy is, Luffy is not a Swordman, Shanks is. Kaido can be the World Strongest Creature, meaning he' stronger than other creature, but it's not that it's impossible to beat him. It doesn't work like that. But he's still the World Strongest, till someone beats him and gains that title.
Think of Football for example, Ronaldo is The Best Footballer in the year right. Messi, who's also a footballer, has better skills than Ronaldo such as dribblings, but Ronaldo's other abilities compensates for that to make him the Best in overall. Think of Shanks and Mihawk like this, sure Shanks haki could still be stronger, but Mihawk ' other skills makes up for it, and makes him the World Strongest Swordman.
Ronaldo >>> tho, don't @ me