I don't know if this subject was talked before or not (which I'm sure it was), but let's see what others think.
If I'm getting this right, there is difference between creatures and species.
- Creature means a non-human being
- Species mean a group of living beings consisting of similar individuals.
So, what I suggest is to simply consider the species as species, and consider the creatures as creatures, instead of writing "Creature Species" in the infobox, which does not exist (Seriously though, what is "creature-species" anyway xD)
If you have any doubts of how we will organize this, we can simply get help from the words themselves. So "Fairies" have -s in it, so they're certainly species. While on other hand, "The Siren" is only one (as far as we know), so she's a creature.
If you have any doubts of what is what, simply comment down below so that we can all decide it with agreement.
(To see the full "creatures", go to a creature page and check the table down below, or simply go to the List of Creatures page.)