Do some divines just MAKE new monsters for literally no reason other then they wanna? Like, Titania made faeries to be soldiers, Cerno made the first werewolf to defend himself (And made a plague), Erasmos made demons to boink, and Morganya made arachne to piss off Gaia, but could there be a divine who, at one time, made a species of monster and had NO intention for it beyond they thought it'd be cool if it existed and they made it exist because they're divines and Gaia lets them use her tools?
There have been plenty of monsters that existed simply because a divine said, "I think this would be cool" or "I want to make my own custom friends/spouse/pet/whatever".
Most monsters are one-of-a-kind and eventually die out, and not all of them get recorded by the World Athenaeum before they pass. These simply get lost to history. Only a very small number of them go on to build a self-sustaining population (like skorpius, harpies, etc.)
Monster forging is a complicated process, it violates World Law, and it's one of those things that everyone knows is a bad idea, but some divines can't resist the temptation to try anyway. Every monster has some unintended flaw and the potential to wreak massive havoc on the ecosystem or society. Monster forging is considered "playing God".
(Even Disgrace was wary about making the camedile because he knew that thing was going to turn out fucked up no matter what he did. I mean, it tried to attack its own creator right off the bat, so...incidents like that are pretty typical when forging monsters.)
So, divines making random monsters willy-nilly doesn't happen as often as you'd expect. But yes, it does happen.