Usopp- "I told lies. And eventually, when I was nearly grown, my mom died peacefully of illness."
Zoro-"My friend fell down the stairs."
Luffy- "I was abandoned by my father, and my mentor figure lost his arm to save me, beaten by thugs and my brother was murdered by world nobles as my entire home went up in flames."
Zoro's flashback is weak. Hell, its not even an entire chapter in length. ANd Usopp's flashback is like a single page. Their histories sucked.
And Robin didn't even get a flashback until 275 chapters, almost 30 volumes, after she first appeared. (And much earlier in the series, Nami didn't get one till chapter 77, despite first appearing in chapter 8.) So… tragic flashbacks up front are not requisite prior to joining.
Even then, Jinbe HAS had a flashback, two tragic deaths in his past, the responsibility of Arlong, now some responsibility for Hodi, failure as Shichibukai, failure to save Ace or WHitebeard, and decades of guilt upon his shoulders. He's had PLENTY of tragedy. (And plenty of emotional bonding time with Luffy and the crew)
ANd we still don't even know how he got his scar!
Its not a random guess of "clearly the missing scar is important because I guess so" its a case of "clearly the missing scar is important because Oda made a long multi-chapter sustained point about it." It's how Oda works, and we've had over 500 chapters to get used to his style.
Oda went through the trouble of removing it for the entirety of the previous flashback, so there's probably a specific story behind it that needs some more context/relevant timing, the same reason he didn't show Hody's portion of the flashback until the time was right to give the full context of the message. (Or the way he saved Skypiea's history for after all the questions had been asked and answered... Robin's flashback for after the Strawhats had already decided to save her no matter what, the full Laboon flashback for after Thriller Bark was done, or Luffy/Ace/Sabo's flashback for after the war was over. He's waiting for the right emotional time to do it, and where it wouldn't break the main action.) Thus, we're probably due for at least a few more pages of flashback focused specifically on Jinbe... which is the perfect opportunity to get some insight into his personal motivation, rather than the island's history.
As the supposed new crewmate, he's having an awfully long time to even hint at a personal dream. Should that be any cause for worry?
Robin had been around for 80 or 90 chapters before we were given even a hint about her being interested in ancient history, and 275 chapters before we started her flashback.
Franky's TRUE dream wasn't revealed until the second he was joining the crew, (before that just building the ultimate ship was enough. Travelling on it wasn't brought in until the last second) and Usopp's "official" dream not until Reverse Mountain, long after he'd joined. We met Laboon in chapter 103, and didn't meet Brook until chapter 442 (and his connection to laboon wasn't until 459 .)
And there's plenty of hints about Jinbe's personal dream, if it turns out to be something about human/fishman relations. (In which case we've been getting hints before he even appeared on camera.) We don't have the exact single sentence easy catchphrase of what his specific goal is YET, but we have a general idea of what it might be.
No. Not having the exact specific phrasing of his personal dream yet isn't a thing at all, when we have some idea already, especially when we'll probably have it by the end of the year, or not long after.
Anybody with anti-Jinbe sentiments really ought to internalize these posts, this really does synthesize all my thoughts on Jinbe joining pretty well. Kudos, Robby.