Probably different versions of the hide-and-seek myth were well known all over Polynesia and maybe they were used (among many other such common simple myths) for remembering the features of the night sky.

Arcturus could in some way have demonstrated some aspect of hiding and searching. Allen:

"Landseer, following La Lande, said that the Herdsman was the national sign of ancient Egypt, the myth of the dismemberment of Osiris originating in the successive settings of its stars ..."

 

If my intuition is right, then there is a connection between Arcturus and the famous Osiris myth:

... Sorrowing, then, the two women placed Osiris's coffer on a boat, and when the goddess Isis was alone with it at sea, she opened the chest and, laying her face on the face of her brother, kissed him and wept. The myth goes on to tell of the blessed boat's arrival in the marshes of the Delta, and of how Set, one night hunting the boar by the light of the full moon, discovered the sarcophagus and tore the body into fourteen pieces, which he scattered abroad; so that, once again, the goddess had a difficult task before her. She was assisted, this time, however, by her little son Horus, who had the head of a hawk, by the son of her sister Nephtys, little Anubis, who had the head of a jackal, and by Nephtys herself, the sister-bride of their wicked brother Set. Anubis, the elder of the two boys, had been conceived one very dark night, we are told, when Osiris mistook Nephtys for Isis; so that by some it is argued that the malice of Set must have been inspired not by the public virtue and good name of the noble culture hero, but by this domestic inadventure. The younger, but true son, Horus, on the other hand, had been more fortunately conceived - according to some, when Isis lay upon her dead brother in the boat, or, according to others, as she fluttered about the palace pillar in the form of a bird.

The four bereaved and searching divinities, the two mothers and their two sons, were joined by a fifth, the moon-god Thoth (who appears sometimes in the form of an ibis-headed scribe, at other times in the form of a baboon), and together they found all of Osiris save his genital member, which had been swallowed by a fish. They tightly swathed the broken body in linen bandages, and when they performed over it the rites that thereafter were to be continued in Egypt in the ceremonial burial of kings, Isis fanned the corpse with her wings and Osiris revived, to become the rule of the dead. He now sits majestically in the underworld, in the Hall of the Two Truths, assisted by forty-two assessors, one from each of the principal districts of Egypt; and there he judges the souls of the dead. These confess before him, and when their hearts have been weighed in a balance against a feather, receive, according to their lives, the reward of virtue and the punishment of sin.

The body of Osiris was torn into 14 pieces which were scattered in the muddy delta of the Nile and then the search began. Possibly Metoro's atua refers to the 14th night of the Moon (or to the 14th month in the year):

Although it was named Otua on Easter Island:

If Arcturus was connected with dismemberment, then Cb1-6 could depict the opposite, viz. reassembling the broken bones ('timbers') of the body ('ship').

Al Ghafr means the 'Cover' and the heliacal position of April 21 could then be its opposite - uncovering (the 'Ship') in order to start sailing again. The beginning of the season of navigation for the Greeks was in May when the Pleiades rose heliacally, but precession may have made necessary a 'realignment' from the Pleiades to the 1st Point in Aries.