After death the "human body" as you are well aware, will either be cremated or buried.
If cremated the body will be instantly turned to ash.
If buried, the body will gradually decay over time.
Either way, the body ends up as powder.
Are you meaning to ask, does a human have a soul? and if so what happens to the soul after death? A totally different question that will generate various answers depending on the faith and religion (or non-religion) of the person who answers it.