He was off-panel for 300+ chapters since Marineford
He comes back to Riku and such praising him, nothing special there
He is then off-panel for 150+ chapters
He comes back at Amazon Lily, where he's saved by an emperor. But negotiates himself to save other marines, heroic shit. But we've seen other Marines do more heroic shit at this point already.
Few chapters later at Hachinuso he's saving civilians from pirates, standard quo marine job.
Where is this again and again happening??? he's done basically standard marine quo stuff where he saves civilians from pirates.
The only person who has been blatantly been cast again and again as something the Marines should be, is Fujitora. Since Fujitora provides an actual change to marines in their core principle of how they operate. No other marine.
Oh now you're doing the thing Smoker naysayers do when they refer to large gaps of page time in a series like One Piece mean anything at all.
Let me help you.
Being the first friend Luffy makes on his journey and ending that arc by leading Shell Town in a salute to a pirate, goes a long way towards making a statement on how Oda see's the rules of the Marines and Koby relative to them, and Koby just like Smoker by virtue of who they are have automatic extra weight invested in each of their actions and how Oda uses their economy of page time, if you're reading with sense.
In Koby's economy of panels he's been more of a symbol and deliberate counter to the model of the Navy as it stands in combating pirates and unless you think the series is going to end with them functioning the same, I'd bet money on Koby in his repeatedly emphasized empathy and conviction in the face of unjust orders/violence is the likeliest representation of a policy shift from Sakazuki and Garp the fist just punching crime.
Garp is the "hero" of the Navy, that title has meaning, Koby is the "hero" of the Navy, his title also has meaning; now it's up to you to add 1 + 1 and see how the mentor differs from the pupil and what that means for the Marines they represent as an individual.
If (and I'm capitalizing this for emphasis) THE CLIMACTIC MOMENT OF PRE-TIMESKIP ONE PIECE isn't singular enough of a moment that with the arcs context clearly point towards a position on the Navy's direction, likely to be followed up on with Koby's character, then I don't know what to say.
Especially given that Koby likely for his hero title specifically due to saving civilians versus rescue as a byproduct of punching.
I'd also say Koby and his feckless cries for surrender on Amazon Lily in contrast with the Marines aggression on a foreign nation and Sandersonia lampshading his "hero" title in a sarcastically meant line, point towards the position of the Marines and how Koby due to the institution he's in inherently falls short of that ideal and will need to course correct; as I predicted Koby would be crying for surrender when we cut back to Amazon lily and that's what I theorized the crux of it may be.
How Garp's being cast right now emphasizes that even more.
Look it's your choice if you want to horrendously read Koby's character but in that case you're not better than all the people who sell Smoker short either due to a lack of imagination or comprehension.
Every Marine saved people, yes; the point is that Koby *excels* at his job to the point that he's given such a title, that's how these things work in the real world and fiction.
A million people could sacrifice themselves and still one will have elevated resonance for one reason or another; you have to be deliberately sandbagging your interpretation to not see what Oda was doing with Koby in Egghead.
Both Koby and Smoker parallel Garp; it isn't scary, it isn't bad, and neither conflicts with the other in how they parallel him.