Without reading the fanfic, it's difficult to determine the main characters. However, if it's about the 'daughter of the land', she is most likely the central character. And given it's a Naruto - based fanfic, there might be appearances from the main Naruto series characters such as Sasuke. They could be involved in her story, either as friends, mentors, or rivals.
In a 'naruto daughter of kami fanfic', Naruto is surely one of the main characters as he is the father. His daughter, who is the key element with her kami - related nature, is another main character. However, depending on the plot, other characters from the Naruto franchise could also be main characters. If the story is about the daughter's training, then her sensei, like Iruka, could be a main character. If it's about a conflict, then the villains from the Naruto world, such as Orochimaru or the Akatsuki members, could also be main characters as they would be involved in the story's central conflict with the daughter and Naruto.
Since it's a Naruto fanfic titled 'daughter of the land', it could potentially be centered around a character who is born from or has a deep spiritual connection to the land in the Naruto world. It might involve her growing up in a particular village, facing challenges like the other ninjas. She could be on a quest to discover her true potential, all while dealing with the politics and power struggles that exist within the ninja villages. It may also include her relationships with other characters, both friendly and antagonistic, and how she uses her connection to the land to overcome difficulties.
Some fanfics might feature original characters. For instance, a young samurai from the Land of Iron who dreams of becoming a great warrior and befriends a ninja from Konoha. This samurai could be the main focus, showing his growth and how he bridges the gap between the samurai and ninja worlds.
It could be Naruto himself as he often is the central figure in many Naruto - related fanfictions. He might be exploring these new lands.
In 'naruto daughter of kami fanfiction', Naruto and his daughter are the mainstays. His daughter, with her unique identity, would be at the forefront. There could also be characters from Naruto's family, like Hinata if she is Naruto's wife in this fanfiction. And then there could be characters from the wider ninja world who are affected by or interested in the daughter's powers. Maybe some of the village elders or other powerful ninjas who want to use her powers for their own purposes or try to keep her powers in check for the safety of the village.
Obviously, the daughter of Discord is a main character. She would be at the center of the story, with her own personality, goals, and growth throughout the fanfic.
Obviously, Spike's daughter would be one of the main characters. And probably Spike himself would play an important role too, as her father. There might also be some of the classic MLP characters like Twilight Sparkle or Rainbow Dash who could interact with her.
Obviously, Beckett and his daughter are the main characters. Beckett is likely to be a protective figure, using his skills and knowledge to try and get them out of the trapped situation. His daughter, on the other hand, might be the source of hope or inspiration in the story, perhaps with her own unique ideas to contribute to their escape.
Obviously, Phoebe's daughter would be a main character. She would likely have her own personality, powers, and goals. Phoebe herself would probably also be a major character, perhaps as a mentor or a source of conflict depending on the story.
Obviously, Cassandra and her mummy are the main characters. Cassandra is likely to be a young girl full of curiosity and a thirst for knowledge about her family. Her mummy, on the other hand, is a more experienced figure, with a past full of secrets and a source of wisdom and protection for Cassandra.