I Am the Ancestral Shaman of Time, Invincible with Sign-Ins

[Transmigration + System + Multiple female leads + Primordial-world setting]

Lin Chuan, a modern man, accidentally transmigrates into the primordial world and becomes Zhulong, the Ancestral Wu who commands the laws of time. He also activates the [God-Tier Choice System]. With the Ancestral Wu on the verge of the Witch-Demon Tribulation, how will Lin Chuan lead the Wu clan out of this predicament?