When Jericho falls, the city is devoted to destruction. It is a whole burnt offering. The entire city is put to the sword and burned with fire as an offering to Yahweh. This is not something that is handled by a soldier or regular citizen. An offering could not be burned with fire lit by men, as God made very clear in Leviticus 10, with Aaron’s sons. This fire came from the altar and was only handled by the priests. This served as a kind of firstfruits of the land, an offering entirely given to God of the harvest of spoils from conquest. After this, all the people could join and eat the harvest.