That is kind of the point - why is the dad who wields a pencil going to have to leave his children in a worse position than a dad who wielded a hammer.
The dad who wields a pencil is paid for his art, and he can use that money to buy a house.
Let's say "a dad who wielded a hammer" is a dad who builds and sells furniture.
Are his children entitled to every piece of furniture this "dad who wielded a hammer" ever built? As it was already mentioned "The dad who wields a pencil" can just as easily buy a house and leave it to his children.
The problem with immaterial things is that they can be trivially copied. In this sense copyright law is more akin to patents: you get protection and possiblity to profit off of your immaterial work.
2. Private property is a false analogy
3. Copyright was established for two reasons: a) to let the author (and only the author) to profit from their immaterial work. b) to facilitate the free exchange of ideas