The Nightmare Tapir retrieved tons of useful information from Zhongli Yan's mind.
The Zhongli Clan had no relation to the Bug Tribe at all. In reality, the real Zhongli Yan was dead. He was just the Bug Tribe's Ultimate Elite that the Queen Mother made out of Zhongli Yan as breeding material.
The benefit of using a supreme genius as breeding material was that these Bug Tribe's Ultimate Elites could mirror the original supreme genius's genes completely and carry on one's memory and inheritance perfectly to blend into the human foothold seamlessly. Moreover, these Ultimate Elites were born pseudo-quadruple mutated. Some of them were even born mythical-level quadruple mutated directly from breeding materials that were powerful when they were alive.