If we consider Carmilla as the 'first female vampire story', then Carmilla herself is the main character. She is a seductive and menacing vampire who targets young women.
If it's about Lilith in some sense, Lilith is the central figure. She has a complex nature, being both a symbol of female independence in some views and a somewhat dark and vampiric - like entity in others.
In some vampire origin stories, it's a man named Vlad Tepes. He was a cruel ruler in Romania. His brutal deeds and his habit of impaling his enemies led to the creation of the Dracula legend, which is closely related to the vampire origin. His reputation for blood - thirstiness made him a prime candidate for the first vampire - like figure in European folklore.
Often, the main character in the first original vampire story is the vampire itself. It's the central figure that drives the horror and the plot. There might also be a victim or a potential victim who is trying to escape the vampire's clutches.
The main characters in the first vampire story are likely to include the vampire itself. It could be a person who has made a pact with the devil or been cursed in some way. Then there are the victims, who are usually unaware of the danger until it's too late. And there might be a character who discovers the truth about the vampire, like a doctor or a scholar, and decides to take action against it.
In many first vampire hunter stories, the vampire hunter's mentor, if there is one, can be a very famous character. This person has passed on the knowledge and skills to the hunter, and their backstory and wisdom can make them quite well - known within the context of the story.
It could be a nobleman turned vampire 200 years ago. He was once a powerful figure in society and now uses his status and charm, along with his vampiric powers, to survive and thrive in the shadows.
As I said before, without more details, it could be different characters depending on the context. It could be Adam if it's a religious context. Or it could be someone like Neil Armstrong if it's about the first man on the moon.
As we don't know much about the 'fu first story', it's hard to say who the main character is. But if it's named after someone, perhaps the main character is Fu.
I don't know as there's not enough information given. It could be anyone from a child experiencing a new emotion to an adult going through a life - changing event.
It depends on which culture's first recorded story you are referring to. For example, in the Epic of Gilgamesh, which is one of the earliest recorded stories, Gilgamesh is the main character. He was a king in Uruk, known for his strength and his search for immortality.
The main character in the first Tarzan story was Tarzan himself. He was a man who was raised by apes in the jungle.