Why probably did the Easter Island residents erect the moai monumental heads?

nobody knows but, it is said that there was 2 clans on Easter island, the long eared people, the small eared people. the long eared people were the rulers. they commanded the small eared people, to build huge heads out of volcanic rock. then rock to the ocean and placed them so the faced into the center of the island so they could look into the tribe. it is also said that the Easter island heads have long ears because that's what the leaders had back in the day. i don't think this answers your question but i hope it helps