Neither dislike or especially like Jinbe so I'm somewhat indifferent on his character.
Oda seems to be tryna fit him into the existing Adult-Trio dynamic (i.e. the older heads on the crew) but it's true that he does lack quirkiness in comparison to the other 3 or any other SH for that matter. He's just a regular dude lol, hence why he feels very out of place.
I see what he brings to the crew with regards to strength and skills, but he lacks personality and the individuality that every other SH seems to have. For instance, putting fighting aside, if the SHs are just chilling on the ship, fcking around everybody has something else to bring to the table but Jinbe just feels like he's there which is why I think he doesn't really come across as a proper SH just yet at least and I don't think being a serious character has anything to do with it tbh, we've seen Smoker for instance or even Law interact with the SHs and they fit.