Right? Like, I at least understand that we're the only ones who can pilot the Warframes, but it should never have come to that! It was their own mistakes coming back to haunt them, and honestly we should have just let the Sentients kill the Orokin high command before defeating them.

Oh, Sentients are more composite-creatures, sent to terraform a distant planet. Earth was becoming slowly unlivable, and when they realized that the Orokin would just ruin any planet they took they had an uprising.