I haven’t finished the campaign yet, but I’m a decent way into it.
Found an audio log where the Harbinger is telling - a human, I think - “I shall talk and you shall listen”. The place we’ve heard that before; meeting the Gravemind in Halo 2 with the Arbiter.
Sooo; I do wonder if this is just a reference or is the Harbinger a Precursor? Or have a direct tie to the Precursor?
Considering Bungie’s use of “O’ Brother Mine” or some such to allude to a similar twist in Destiny 2 (I don’t remember the exact nomenclature for the species and the quote) I’d be itchin’ to believe it’s the former.
Maybe it’ll be cleared up for me as I advance the story, I just wanted to drop this observation here for discussion while it was fresh in my head.