I also think that the first depitction of how Oda envisioned the crew is very diverse, as you say. We have a fishman, a skeletton, etc.. I think you somehow see that he was very young at that time, since those first few drawings seemed to be out of someones pen, who wanted to draw a rather "cool" crew.
Why not categorize Nami as a thief, if we go by profession? Than it would fit again.
Anyway, here is why I think Lucci will be the last crew member of the SHP (One important hint, which I had not listed there was a statement of Jinbe from Wano, who said that what the SHP ultimately needed, was one person, who could observe the state of the battle calmly [chapter 979]). One or two more hints are missing - sorry for that):
Main hints