The wisdom behind Allah Ta‘ala appointing Nabi Aadam (‘alaihis salaam) to be His vicegerent on earth, instead of the angels, is that man has the ability to administrate and manage the affairs of the world.

The world and all its substances are harmonious and compatible to the human nature. Hence, in order for one to be able to administrate and manage the affairs of the world, he needs to be from the human species. Being the vicegerent of Allah Ta‘ala on earth means that man will have to fulfil the laws and injunctions of Allah Ta‘ala in the world and uphold justice among the creation. Man will have to execute punishments to people perpetrating crimes such as usurping the wealth of others, killing people, etc.