So many good ideas coming through.
Just for my 2 cents, I would prefer to steer away from birds and humanoids if we could. I feel that aquatic mascots are under-represented (basically only the sharks and eels) and given that Australia is an island nation and some unique marine life I think we could have at least one if not 2 more.
I mean, pre-super league/mergers we had 4 bird-related mascots (Roosters, Sea Eagles, Seagulls and Magpies) and there is and has been a huge representation of humanoid ones (Raiders, Knights, Cowboys Storm [kind of given their mascot], Titans, Warriors, Steelers).
Just a personal preference of mine.