Why did he put "a" in front of a person's name?
Native speaker’s answer
Rebecca
He put "a" in front of names here because he is not referring to the names as the names of individual people; he is instead using them to refer to a particular type of person. So "a Jackie" refers to a type of person who is like Jacqueline Kennedy, former First Lady of the United States, while "a Marilyn" refers to the type of person who is like the Hollywood star Marilyn Monroe.