The problem is that one of the missions of most zoos is to serve as an educational institution. That means a zoo has the duty of disseminating scientific knowledge as accurately as is possible in light of its other missions. Since creationism is nonsense, a zoo has the duty
not to have an exhibit on creationism except, in light of contemporary politics, to show how it fails as science.
As far a culture is concerned, I don't see how the statue of Ganesh promotes Hinduism. If someone wants a picture of Noah's Ark (with no promotional materials) in addition to this statue, then I would have no objections.