Question

why does the process of a child changing into an adult human being cannot be referred to as metamorphosis.

Answer 1

the process of a child changing into an adult human being cannot be referred to as metamorphosis. becoz
Metamorphosis is a biological process by which an animal physically develops after birth or hatching it is not done in human beings

Hope its help you

Answer 2

During metamorphosis ( meta- beyond, morpho- change) the organism's body structure is COMPLETELY changed and may involve growth/desolvation of certain organs through cell growth and differentiation.
In humans, when a child grows into an adult, no such large-scale changes occur. Hence, human growth cannot be termed as metamorphosis.