The first and original definition of "person" is "a human being".
An alternate, legal definition is "a corporation."
Lets break down that definition and dive deeper into the abstraction.
A law is a piece of paper with words written on it that some people agree on.
A corporation is created by filing articles of incorporation. Again, this is a piece of paper with words written on it.
So, in reality using law to define a corporation as a person you have a piece of paper saying a piece of paper is a human being.