>>535151283
>>535153585
The original answer would've been the same-ish twist Halo was supposed to do with the forerunners, that there were ancient human aliens (either literally humans, or something the we evolved from) that built the traveler (and Vex). That race was intended to be the same that later built the pyramids, after subset of them got booted. The traveler was just their magnum opus. A giant hollow ship.