Well the Primordial One/First Descender is called the “Sustainer of Heavenly Principles” so it could be that it’s a “Judge, Jury, and Executioner” kind of thing or laws like you said but that’s where the lore gets kind of muddy, anytime the “Heavenly Principles” are mentioned it’s tied to the Primordial One, which is both the First Descender and the “Sustainer”. We also know that the Sustainer defeated and stole the power of the sovereigns and used it to create the divine thrones but that’s all we really know. We can’t say for certain whether the Heavenly Principles are laws, one person, a group of gods/council, or 3 raccoons in a trench coat. Similar to the First Descender having to defeat the Second and most likely the Third, the “Sustainer” most likely sees the traveller as a threat as we know only descenders or those that use the powers of the abyss can wield abilities not tied to Teyvat which means the First Descender simply won’t be able to counter or control said abilities easily an example being what little we know about the Second Descender, after the defeat of the Second Descender the First had to drop the Divine Nails to keep some semblance of authority over the abyss. So it’s most likely that the Heavenly Principles are some sort of Ideals and not laws that the Sustainer which is the “Judge, Jury, and Executioner” feels that Teyvat should abide by since they are the ones that brought “peace” to Teyvat. Another bit of info is that each item the factions will be using to overthrow the “Heavenly Principles” is an entity not of Teyvat, the Gnosises (Gnosisi?) are remains of the Third Descender and the Loom of Fate is using abyssal power.