Primordial Spirit is a concentrated form of spiritual power, without a physical body, it lacks a layer of protection.
The physical body can be considered a shelter for Primordial Spirit, whether from lightning strikes, electric shocks, water and fire attacks, or evil qi invasion, the body stands as a gateway, blocking them outside.
However, in the Cultivation World, physical bodies have never been emphasized; what's valued is the transcendence of the Primordial Spirit, abandoning the flesh to ascend and become immortal.
Thus, immortals are divided into Scattered Immortals and True Immortals.
Only True Immortals are truly transcendent, Scattered Immortals lack the physical form, hence their foundation in cultivation is deficient.
Humans consume grains and cereals, producing Essential Qi in the Dantian through flesh, bones, and blood.