People always wonder what Neelix is doing on Voyager, is he the cook, the moral-officer, the comic-relief? What is he doing joining the senior officers during debriefing? Is Janeway insane?

Nope, Neelix is basically the logistics-officer.... basically the ship is understaffed and anyone with any kind of engineering or scientific know-how is needed to actually run the ship, suddenly this weird alien appears with years of trading and storage experience and Janeway just puts him to work organizing and cataloguing, simple, boring with also incredibly useful work.

Voyagers buys spare parts and it's up to Neelix to describe, barcode and input it into the system. Food? Well he is also the cook, so let's put him in charge of that. How much raw materials does Voyager have of that or this exotic metal? Neelix has already done the work.

Neelix is basically the foreman at your local warehouse, it's simple work but highly essential. All his other jobs like cook, moral-officer, diplomat etc just grow out of that function.