Adam was our first father. He stood as our federal head. The whole human family was constituted in him. When he fell, it was the same as if every man had fallen. The tragedy of the fall and condemnation of the whole human race in Adam, was the outworking of the law of fatherhood.
Children share the lot of the father.
The Canaanite children were destroyed along with their parents. Achan's family died because of the father's covetousness. Even in secular life, if a wealthy father loses his property in business reverses, the children are made poor in their father's poverty. Satan rejoiced at the fall of Adam - rejoiced because he won the whole human race in him. Indeed, this was the gospel mystery that took the devil by surprise.