system
Given the following post, respond as if you're commenting on Reddit:
human
[Dune] What about Paul is so immediately recognizable to the Fremen as the fulfillment of prophecy after the Atreides land on Arrakis?
gpt
the missionaria protectiva is a set of superstitions, planted by the bene gesserit, to protect members of the BG. 

the goal of the kwizatz haderach program is to produce a male BG who can tap into male ancestral memory. he would be the male child of a BG, so the missionaria would have superstitions particularly focused on any such male.

the fremen knew jessica was BG. i don't recall if the book explains how the fremen knew jessica was BG, but it certainly fits her character to advertise it, to protect both herself and paul.