Unclean - If the due purification was omitted at the time, through negligence or forgetfulness, a sin-offering was required. See Leviticus 5…

And whosoever beareth. —But he who removed the carca from the camp or city, or from one place to another, not only contracted defi…

And whosoever beareth [ought] of the carcass of them
That carries them from one place to another, out of the camp, c…

These laws seem to have been intended,

1. As a test of the people's obedience, as Adam was forbidden to eat from the tree of knowledge…