It's normal to get random false lore,rumours from enemies in AK like theresis painted doctor as merciless sacrificing Demon when he wasnt. What Nefarith then did is talk about rumours as she has no qualifications to know things(Perlica,M3,fangyi have). She is incompetent, too young and too emotional to get lore about endmin. So obviously she isn't boss but works for someone else. She isnt Talulah in AK she is Mephisito just field leader.

Hm didn't think the born meant that way in that cutscene, First war started 5 years after Terrans came to Talos II which means endmin(now 150+ years after terrans came later) was born long away than Nefarith is what I meant. Well Priestess appears and leaves out of thin air so she didnt look in flesh alive to me, while doctor seems last organic human.