Okay so we all know the descenders right?
People that come from beyond Teyvat, are over Teyvat's natural laws and are able to influence Teyvat's fate yada yada yada.
We also know that the heavenly principles [or primordial one/ Phanes] were the "first descender" and Nibelung was the "second descender"
Nibelung came to Teyvat back when there were only the light realm and the void realm, he was the first one who came to Teyvat from the outside. [As far as we know]
Yet the heavenly principles are called the "first descender" and Nibelung is the second. From their perspective, Nibelung "arrived" in Teyvat and then the war of the funerary flame happened. Rather than Nibelung leaving and coming back.
So this makes me think that descenders are a made up concept by the heavenly principles. Being a descender doesn't mean being able to influence Teyvat's fate, it means they're a threat to the heavenly principles' power.
And what do you do with threats? You eliminate them.
Nibelung? Killed in the war of the funerary flame.
Saarelainen? Killed and his body was carved into the 7 Gnoses.
The Traveler? Now this is where you have to hear me out.
I personally believe that the Twins weren't descenders when they first landed on Teyvat and our twin first arived in Khaenri'ah
Asmoday already switched sides/ turned on the heavenly principles at the time she keeps us from leaving. That means, she basically separated the twins so they would stay in Teyvat and change it's fate.
Asmoday made the traveler into a descender by making them stay in Teyvat
Basically saying, the heavenly principles are an evil bitch [I'm biased, I love my 3 moon goddesses and Niebelung] and they're going to be the final boss.
Lmk if this makes sense and feel free to ask me lore questions in my asks, my brain is overflowing with info.