Another quote:
Ah, yes, Reapers. The immortal race of sentient starships allegedly waiting in dark space. We have dismissed this claim. -Turian Councillor, Mass Effect 2.
I think his characterization is off from previous Halos, if not the books.
And the Forerunners were aliens, according to Bungie. Read Halo 3 terminals. They did leave an option for them to be humans earlier on, and apparently some Bungie members felt that they should have been humans. But officially the Forerunners are aliens. Not 343i's decision. (Overall, i liked Halo 4 campaign, it was mostly the Chief-Cortana interaction didn't like. Also prefer the Forerunners to be aliens).
But perhaps it is better to take this to PMs or make a thread about character portrayal to continue this, no?