@miriam Cute concept! Your composition looks great. I don't think having (or not having) specific animals or animals from the same region would affect your concept, so I would go with which direction motivates you most.
I personally like the human garage idea, but a creature garage assembled from nature and stuff would also be cute if you want to go that direction.
I don't know anything about aerodynamics (so I could be totally wrong here), but I'm not sure if the glider alone would be enough to get him off the ground? Maybe including a propeller on his contraption or a fan behind him would give him going (thinking of Chicken Run, lol). Although thinking about it, his strong jumping legs might be enough to get him into the air...