Creatures Caves

It's up to the company, really. The C2, C3 and new Creatures Online Shee don't look all that similar, but technically they are all "official". CLabs/Fishing Cactus have never flat-out said that one version is "more official" than another, but typically in game series the newest version is considered the "most official".

From an in-universe perspective, I like to think that the Nornity statue was a stylized depiction of a CO-style Shee; since C2 takes place thousands of years after C1, it would naturally have eroded quite a bit since we last saw it. By the time the Ettins got to it, it wouldn't have been so clear what it originally looked like. And the Ettins themselves probably hadn't seen a Shee in long enough to remember what they were supposed to look like, the poor dears.

The C2 Shee in the preview image would appear to be "based on" the statue (if the C2 statue really is the C1 one), so we could suppose that it is a reconstruction created by the Hands based on their findings.

That's my best guess, unless there's secretly a race of Shee Morlocks hidden somewhere deep underground that we haven't heard of yet.

The C3 Shee isn't too different from the CO Shee... his ears are shorter, his face is wider, and his eyes are a bit bigger (unless he was just surprised to have his picture taken), but that could fall within the range of individual variation. We know the Shee genetically engineered themselves (eg. to correct their eyesight), so it's plausible that they could have a lot of variation.

Of course, that's just my take on it.