The laws of birth, aging, illness, and death weren't only about humans, the world, and the myriad spirits, but also about different worlds.
There were tens of thousands of worlds in the Sea of Realms, and they could be counted as the Great Realm, the worlds, and the realms.
It was based on the number of Immortal Ascension stage cultivators the world could accommodate.
Due to the existence of the Immortal Ascension stage cultivator, some worlds that should have been heading toward "death" were still struggling in the Sea of Realms.