It’s likely, I think. Like, very likely. We know the whereabout of MIA Aschera Tepes (Yuu’s sword, as a demon named Asuramaru), but just how did the Hyakuya sect/the JIDA manage to get their hands on him to begin with? Moreover, the matter of Saitou and his separating himself from the vampire world (also a few centuries prior! we can’t tell if it coincided with the disappearance of the 1st progenitor and Krul’s brother or not, but is it really a coincidence? I highly doubt it). So as a wild theory, the one actually pulling strings is not Ferid (he didn’t mastermind everything, and there are lots of things he doesn’t know himself, as it’s pretty clear from chapter 4), and not even Saitou, but what if it’s the 1st progenitor himself, and Saitou simply serves him/her.
To boot, the Michaela factor might tie in with the Seraph experiments. Like, where did humans even obtain whatever it is that allows them to try and turn other humans into Seraphs in the first place? And keep obtaining, as those experiments blossom in different parts of the world. So far, it’s somewhat likely that from boys/men carrying the Michaela factor, which makes that factor pretty much the dormant angel gene, and those boys/men not quite human from the start. A theory, anyway.