I think it harkens back to an old Twilight Zone episode that came out some years earlier, in which aliens arrived on our planet, with the promise that they would help man. In fact, they even had a book with them titled \"How to Serve Man.\"

I haven't heard this episode in a long time. I will be listening to it
this weekend. It is from March 1982.

I don't really see the connection between using the bones of the dead to make musical instruments (a very common practice among many indigenous cultures) and a cookbook for cannibals, lol.

Only later did someone decipher it to the point where humankind discovered it was a cookbook.