MYTHICAL CREATURES. This is my spin on it. Some might stay the same. (Any Age)

Max- Siren

Nikki- Dryad

Neil- Igor (Lol)

David- Werewolf

Gwen- Medusa

Preston- Dragon shifter. (He can shift into dragon form)

Nurf- Cyclops

Ered- Ghoul

Space Kid- Griffin

Dolph- Satyr

Nerris- Elf

Harrison- Nāga. (Thanks commenter)

Taunise-  Cecaelia (Lol she needs a fishbowl with wheels to get around)

Carlos- Shape Shifter