Didn't even think about those stereotypes, Min Min even falls into two of them.
In some fairness, Min Min is a fighting game character, so the fact that she's a martial artist is just kind of a natural consequence of the setting and she doesn't stick out amongst the cast for that reason. It is true about the food association though, I hadn't thought about that before.
What would she do that the Inklings don't already cover?
I'll spare the long details here but back when Smash Ult was first coming out I put together an entire potential moveset for Agent 8, the lead character of the Octo Expansion, normals, specials, grabs, the whole works. There are a ton of weapons and abilities in Splatoon and S2 that aren't covered in Inklings and gives tons of potential for a different playstyle:
E-liter (she even wields it with her amiibo!), Curling bomb, splat brella, splat dualies (useful for dodge rolls too), octobrush, suction bombs, inkjet, splashdown, luna blaster (I made this their down air--meteor potential if you land a direct hit!), the list can go on and on if you want it to.
Like I said before, folks who think Agent 8/Octoling/Marina would
have to be an Inkling echo are really just not thinking about it very much. I think if Marina were made playable it would be along with Pearl as an Off the Hook duo character but I think that would still count pretty well.