That last point is somewhat disturbing, because it suggests that at some point between now and then, we have ceased to exist in our present form.
Since I truly believe they are using time/space portals, they are from both our past as ET and our future as us. I think we started as ET and in the future will come full circle to have the same technology as used in the past.
I think they are inter-dimensional in both time and origin and not just one entity, but several from different times and origins. And based on ancient writings about battles between these entities of advanced technology, it is possible that we have already had our battles between us and them several times during our linear timeline and may have more in our future.
Because for these entities time or origin are not linear or singular.
Interesting hypothesis.