No, we do not devolve back into "primordial ooze" once we die. The concept of "devolving" implies a regression or reversal of evolutionary progress, which is not a scientifically accurate representation of what happens after death.
When a person dies, their body undergoes a process known as decomposition. Decomposition is a natural and gradual breakdown of organic matter by the actions of various microorganisms, such as bacteria and fungi, along with other physical processes. The body's nutrients and elements are recycled back into the environment as part of the natural ecosystem.
The idea of "primordial ooze" generally refers to the hypothetical pool of organic compounds that existed on Earth billions of years ago and is thought to be a part of the origins of life. This concept is related to abiogenesis, which proposes that life arose from non-living matter in the distant past.
While decomposition after death returns the elements and nutrients of the body back to the environment, it does not lead to the re-creation of a primordial ooze or the reversal of evolutionary progress. Evolution is a process that takes place over vast spans of time through the mechanism of natural selection and does not involve the decomposition of individual organisms after death.
In summary, once a person dies, their body undergoes decomposition, and the elements that make up their body are recycled in the natural cycle of life, but there is no "devolution" to primordial ooze or a reversal of evolutionary progress involved in this process.