Not to be a dick or anything, but we know precisely what the moai on Easter Island were for. They were religious figures of the Easter Islanders. They grew increasing large and numerous as the tribes of Easter Island began warring with one another, in an attempt to display the "greatness" of each tribes respective leaders. It is in part due to the obsession with symbolic greatness and the construction of the moai that led to the eventual downfall of the Easter Island culture, as can be seen by the eventual grass-roots moai destruction activity during the proper collapse of the island's society in the 1700s and 1800s. The few Easter Islanders that survived the end of their civilization described this back when they were first contacted.

Easter Island isn't some big mystery, unless you don't read history books.

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