Oda likes setting up a thematic connection between the fights of the straw hats and their arc opponents.
Sometimes the themes are as simple as Girl vs Girl, with Nami vs Kalifa and other times they can be Match up counters such as Usopp vs Perona and at the top it can be straight up ideological differences such as Chopper vs Hogback.
Now here we have Jimbei vs Who's who and if we assume that this is indeed Jimbei's main fight, then we got to ask, what will be the thematic connection between the two?
First let's assume the theme is much stronger than something like Girl vs Girl. I assume the theme is much stronger because oda is setting up an actual past between the two. Obviously when we get the past, we will actually see the theme play out fully and clearly but as of now, let's speculate.
The theme between Jimbei and Who’s who is rank and position. Their first interaction is even specifically about Ranks and positions. Who’s who refers to Jimbei as former Warlord and Jimbei prefers the title “Helmsman of the strawhats”. I believe even their past that Jimbei and Who’s who are going to share will be about Jimbei’s Warlord position and Who’s who wanting that position or envying it in someway. Jimbei is going to represent the perspective of treating ranks and positions as opportunities to have more responsibility since Jimbei became a warlord specifically to take on the responsibility of reducing the prejudice against his people whereas Who’s who is going to treat ranks and positions as ways of gaining power and prestige.
Now it's not a given that since Ranks are the theme of the fight, then Who's who must be on the exact opposite side as Jimbei. For example we've seen Franky vs Pink where the theme of the fight was Machismo and the two fighters were very much on the same side. In fact at one point they just start trying to out macho one another instead of actually fighting. It wasn't a fight about one guy being effeminate while another is macho or anything like that.
Therefore it's not a must that who's who has this perspective on Rank simply because that’s the theme. But I greatly think this is his view. And I think so because he's not a good person really. And I don't mean the cliché "good vs bad", I mean he's not a good person even on one piece standards. In a roundabout way, we can say Pink is a good person since he was so loyal to his men and very remorseful for hurting his wife. Stuff like that. When two good people fight, they tend to be on the same side of the theme but it’s the opposite for when a good and bad person fight. I think Oda has shown us Who's who is not this type of good person at all and he has shown us this specifically when referring to Ranks.
Oda told us this using the Drake double cross. Immediately this entire scenario is an extremely scummy thing. Who's who was playing some long game for multiple chapters lying even to the audience as well as drake and being presented as some kind of rebel in the beast pirates. He was talking about killing queen and not respecting the hierarchy of the beast pirates wanting to challenge The calamities and it seemed cool. It's always cool when there's a rebel within the enemy group, even if they don't actually become good guys. Hence why people liked Ulti so much for talking disrespectfully to kaido even though she's a pure diehard for kaido. The slight rebellion in her was enough to make her a favourite.
And Who's who was DECEPTIVELY presented as the ultimate rebel. And it was all a lie. Who's who doesn't want to kill Queen, he's actively on a mission under queen himself. There's no "Who's who doesn't respect the hierarchy of the beast pirates", he straight up enforces it. Who's who says about Drake "I can't believe a spy rose so high up to even the tobi roppo. It's a disgrace". This man actually puts rankings on a pedestal and respects them so much that he considers it a disgrace when this happens. He's not even a Calamity. The guy is actually wanking just his Tobi roppo rank like its a very big deal to him and he's getting personally offended when it gets bismerched. The guy's entire intro was a lie.
It was an intentional misdirect that Who's who could be the ultimate rebel and people even thought he was like Gin, another of one those Good people who still happen to be enemies. Others even thought that his rebelliousness could lead to him either changing sides or just going rogue and attacking a calamity just Coz he maybe had some really interesting beef with a calamity that explains all his rebelliousness. Nope. He was working for Queen the whole time. And oda knew what he was doing presenting him like this yet he isn’t. He wants us to feel betrayed by this and not see Who’s who as a good person.
Oda knows that Ulti will be liked for her mild rebilliousness and so he knows Who's who will be the biggest draw for his extreme rebilliousness. Oda knows this and that's why the drake double cross works best. It both blindsides drake and blindsides the reader. Who's who is not the cool guy. In fact he's a bad guy. Like an actual bad guy. His association with Queen who's one of the worst guys in the crew and just the general idea of him using such a cheap trick on drake and finally the lying to the audience themselves that he maybe is a Gin or Pink type character but then nope, he's just scum.
This is what convinces me that Who's who is an actual bad person in One piece standards and that's what makes me think he's going to be on the opposite side of Jimbei’s ideology when it comes to Ranks and positions. There’s even a slight nod to this in just their first interaction. Who’s who apologizes for calling Jimbei a warlord when he wants to be called Helmsman. This is fake of course. We’ve established Who’s who is a liar. And there is no way someone who gets off the power that comes from Ranks so much would actually consider Helmsman a better title than Warlord. And so that’s why Oda specifies that their flashback is about Jimbei as a warlord. Who’s who will belittle the helmsman title not realizing that Ranks only matter to Jimbei when referring to the duties associated with the ranks and not simply power and prestige.