The majority of the world has the Mortal Physique (凡体); any mundane person has this type of the Physique. It is the weakest Physique both in terms of physical strength and Blood Energy, so it is despised by the Cultivators. Body with Mortal Physique is extremely weak; its muscles, bones, blood, and flesh are all extremely feeble.
However, the Mortal Physique has one great advantage over other Physiques. While other Physiques are confined within their Family, the Mortal Physique didn't belongs to any Physique Family. It can be cultivated into any level and type of the Physique, from Houtian to Immortal, and only then it will be confined within its family as any other Physique.
Of course, to cultivate the Mortal Physique into a higher level is not an easy task. To accomplish it, the cultivator will need a formidable Physique Merit Law, extremerlly strong willpower, and a high grade Physique Paste; the higher the grade and quantity, the better.
To successfully increase the Mortal Physique into the Xiantian Physique is already a monumental task; monstrous efforts must be exerted. Since the probability of success is very low, no Sects are fond to invest so much resources and efforts into someone with the Mortal Physique, so the Mortal Physique's only advantage is mostly ignored and forgotten.