A hotch-potch of traditions, certainly (hand of glory, 'obby 'oss, maypole dancing, the morris lock and so forth) but that's actually in keeping with the story. Remember that what happens on the island is not supposed to be a tradition from time immemorial, but something the Lord Summerfield's grandfather revived/created/threw together to help him introduce new crops. It reminded me of the way a religion in John Wyndham's "The Chrysalids" was created as a means of passing on scientific knowledge in a society which could not afford scientists.

You can treat the Wicker man as just a horror film - and I think its a good one - but it does seem to me to warrant more thought than that. There are points to mull over about the nature of religion for example, that are very relevant to today. Ditto authority.