After posting my extended thoughts on the Mantle and the Forerunner, I thought of another issue that perplexed me. In the Haloverse, aliens are both mortal enemies of Humanity but also their reluctant allies, ala the Sangheili.
And lets not forget Humanity's inheritance of the Mantle and the Forerunner existence, which calls for protection of all life in the galaxy. However, this raises an interesting question; should Humanity accept other sentient races, or should they actively exterminate them, especially if it is in Humanity's power to do so?
This is notable because Humanity's experience so far with alien species is made up of a near-fatal war, and a ravenous parasitic collective. Despite the small alliance with the Sangheili and the false one with the Kig-Yar at the Rubble, they have had little but violence and hatred with aliens. Shouldn't this be breeding a huge amount of anger, fear, revulsion, and hatred of non-human life?
Hypothetically, lets say that the Forerunner were different. Instead of being the kind "guardians" of the galaxy and valuing non-human life, they actively hated it. They pretend to be guardians, for their Mantle instead calls for the supremacy of Forerunner/Human life over all others, and the best way to ensure its integrity is to purge the galaxy of all non-human life.
So they set up a subtle plan to "protect" the galaxy while studying these other and invariably inferior forms of life, all the while preparing their tools of extermination. So then comes along the Flood, the party gets going, and the Forerunner, in their retreat, find Humanity. They quickly categorize Humanity as worthy of joining them, index Earth's biosphere, and then take Humanity to the Ark.
They fire the Array, purging the galaxy of the Flood and all non-humans/Forerunner, save for those samples that are aboard the Ark. Having the information they need, the Forerunner then kill every non-human sentient on the Ark, and return Humanity to Earth.
As Humanity matures and goes into space, they find a galaxy empty of life, which they move quickly to occupy. Eventually, they encounter the Forerunner, who explain some of their history and invite Humanity into their fold. Here, Humanity develops rapidly and is part of the Forerunner empire, but then they discover that the Forerunner had purged the galaxy of every pre-existing sentient race, preparing the galaxy for soley Human habitation.
How would the Humans react to this revelation? Would they see the Forerunner as noble and having Humanity's interests at heart, or as something else?
The question that I am asking is, does the Halo story tell us that alien races are enemies of Humankind and should be destroyed, and that Humanity is superior to them, or that they are to be accepted as a fact of life?
If you had the power to either wipe the galaxy clean of all life except for Earth, would you do it, knowing that this will ensure Humanity's safety and uncontested dominance of the galaxy?
Or would you decline to do so, and take your chances with an uncertain future in a populated galaxy?