: It's clear that the humans in the terminals are not directly associated with
: the Forerunner civilization, but why they fascinate Librarian is unknown.
: Some speculation argued they might be a different species, some
: speculation argued at the time that it only made sense if it was a
: different group from the same species (whose existence surprised the
: Librarian and led her to wonder about the Forerunner civilization's
: identity).

snippet from IRIS episode 5 transcript

The anomalous world is in a perilous location beyond the line.
{//} (THE SECRETS IT HOLDS MUST BE PRESERVED)
{//} (PLANS WITHIN PLANS WITHIN PLANS)
The inhabitants; these unique denizens, must be researched.
They may hold answers to our own mysteries.

Note that the images being displayed in the video are not images of humans; they are images of: bacteria, protists, plants, locations on earth, etc.

What Forerunner mysteries would earth life and humans answer?

All life on earth shares a common genetic code and, although the genetic code is not entirely arbitrary, the fact that all life shares the same code (with some instances of minor modifications) is a major indicator that all life on earth shares a common ancestor.

We also have the fossil record, genetic evidence, developmental and comparative anatomy evidence to show that all the organisms found on earth evolved here. They are not imports from some other planet.

Now if you find a planet with a human population on it and you didn't expect to see them there then you would have a minor mystery. But the answer to how they got there would be, roughly, someone with a space ship took their ancestors there at some point in the past.

OTOH if you find out:

• that all life on earth evolved here
• that humans and yourself are part of the continuum of life on earth

then it is extremely likely that you have found your homeworld as opposed to just an isolated colony of Forerunners on some backwater planet.

If your own homeworld and origins were a mystery to you then the discovery of earth would be of profound importance to you and you would be a great deal wiser as to where you came from.

The idea that all life is related is profoundly beautiful and earth is beautiful and finding that it is your homeworld makes it even more beautiful and precious to you.

I find that connection between F and H: beautiful. It has more resonance with me than the idea that we are just these guys or the idea that we are L:'s genetic experiment/pets, made special by DNA magic.

I liked the idea that we shared some of the F guilt by being related to them. And that relation makes GM's rants make more sense. All that sins of the father stuff would make sense - and it's biblical ;-)

I don't like the notion that descendants inherit sin from their ancestors. I think that it is a silly notion. But my dislike of the concept is separate from my appreciation of how well that biblical notion tied into the biblical themes of the Halo story.

: The H==F argument doesn't rely on the Forerunner/humanity not being killed
: off by the Halos. If anything, it's necessary to the narrative.

Yes because if we didn't survive then we wouldn't be an embarrassment to the Covenant religion.

In addition the actual quote is:

ARBITER:

And those who made the rings? What happened to the Forerunners?

343 GUILTY SPARK:

After exhausting every other strategic option, my creators activated the rings. They, and all additional sentient life in three radii of the galactic center, died ...as planned.

All sentient life was extinguished, not just the Forerunners, and yet several races survived including humans.

We have been told why this is so (reseeding).

Finding humans alive after all species where wiped out does not mean that F!=H. It suggests that either L: managed to catalogue some natives of earth or Forerunners from the Ark used the portal to settle on earth after the event.