Technically, it was created for people who owned homes (and other real estate) at the time the law was passed, and their heirs.
The longer you have owned a property, the more of a tax break you get at the expense of a person who bought property more recently. Basically, it created a society where long term land owners and their heirs have even more of a step up than newer or prospective land owners.
And the longer you own property in CA, the more incentive you have to support prop 13. Quite an innovative way of creating a class divide.