- last post: 01.01.0001 12:00 AM PDT
The Covenant are a collection of species who are focused on collecting Forerunner artifacts and ridding the universe of Human life.
Take a look at a Jackal and an Elite. They are totally different. Elites are much taller than Jackals, Jackals have a different shaped head to Elites, Jackals and Elites have different body shapes.
It is true that all (or most) species on Earth have red blood, so I'd point to Jackals and Elites coming from the same Planet. In my opinion, I reckon the The Prophets started off the Covenant by enrolling Elites and Jackals first, then Hunters and then Grunts. They saw the Grunts as an easy target to enroll because although they were weak, they have huge numbers. So although they were allowed into the Covenant, they are the inferior species because they are most weak overall.
PS. I wouldn't guess when the Brutes and Engineers would be enrolled into the Covenant because I haven't seen them in battle and therefore seen how they are treated by others. I would guess they are treated quite highly because Engineers are great at fixing thing and Brutes are probably the strongest species (according to what people have told me, people who have read the books).