lol...thanks for asking!
Cubbi started out as a cute addition to the crew...honestly because Steve (the artist) did a character design that had popped up now and again in strips (you can see an anonymous Cubbi in some old strips).
I loved that little guy so much, I wanted to make him a secondary character...then he sort of joined the group.
When I discovered (or figured out, or wrote...whatever) that Cubbi was raised by bunnies, that made his character clear to me.
Goblins (oh, this is all my opinion, btw...) have a terrible, ass-backwards culture. They do sacrifices, constantly have tribal warfare, and have superstitions that don't actually contribute to gaining access to the powers they get from their Gods.
As individuals, however, Goblins are just about as capable as any other race, just smaller. The strip started because Gabo (and in his own way, Nub) reject parts of their goblin culture (again...Nub loves some of it). Making Cubbi somebody that was raised outside of that group, gives him the potential to do all kinds of things.
To be fair, I think the recent events (the wings) was a happy accident of Gabo's spell AND the flute...again, just my opinion...open to other theories!!

Mike