Well, human beings about 2000 years earlier used to bathe without soap. In fact as late as until a hundred or so years ago, soap was so expensive that only the very rich could afford it.
Soap basically loosens the dirt from our hands and body.
It dissolves in water. The soap in the water surrounds the specks of dirt on our hands and loosens them from our skins. As we move our hands, the specks of dirt float away in the water, leaving our hands clean. Soap is made from different oils and fats. Oils and fats such as coconut oil, olive oil and whale fat and other animal fats go into the making of soap.