we both have incorrect facts in our posts. the precursor are from the past, before humanity even. but also the descendant vex are also from the past, they have just survived to the future. or have they? Perhaps the grimiore is referring to the golden age humanity, in which case they would truly have been around during the time you and I are in. Also the vex ability to teleport through time leads me to the conclusion that the descendant vex are from the past, but simply traveled through time. also precursor vex show up in the blackgarden strike, and the final boss in the black heart fight closely resembles the structure of precursor goblins and hobgoblins.