There is a difference between having an elemental wheel, and having elemental strengths and weaknesses. Not having a wheel doesn't mean weaknesses still don't occur.

Earth, Water, & Wind seem to be the defensive/healing elements. Creatures like moles and spriggans would be highly Earth oriented. Crabs and jellyfish would be Water. Birds and flies would be Wind.

Now looking at the destructive elements we have Fire, Lightning, and Ice.

Fire could be strong against Wind creatures and defenses (i.e. Wind fans the flames), mediocre against Earth creatures and defenses (e.g. Stoneskin), and weak against Water creatures and defenses (e.g. Aquaveil). Lightning could be strong against Water, mediocre versus Wind, and weak against Earth. Ice could be strong versus Earth (think glaciers), mediocre versus Water, and weak versus Wind.

So just because there isn't a "wheel" doesn't mean that we won't still strategically use strong and weak elements.