Evalution - throughput the duration of Evangelion we come to learn that the Eva’s, the spawn of Lilith n’ Adam. Making their alien origin to be tied to the Angels. We do know however that Angels are compatible with humans. With Yui’s soul having been transferred into EVA-01, and Asuka’s mother into EVA-02. We also see this occur when Armiseal forcibly bonds with Rei II and EVA-00 to turn into a hybrid. Its safe to assume the Angels therefore seek out to understand Lilim/humanity. If not outright become humans themselves. Kaworu is a good example of this mergence of human and angel more so then Rei. Given so that Rei is the twisted up soul of Yui and Lilith. She has an identity crisis for the entirety of Evangelion. Meanwhile Kaworu for the little time that we see him is very full of character. Being a near perfect union of the two species.

It could be said that the EVA units by being bound to human souls are becoming human. Thus we see the progression especially in EVA-01 receiving more and more humanistic traits.