Well, in a fanfiction where Naruto travels to the past, he could meet his parents when they were young. He could also learn new jutsu from the past ninjas that were lost over time. Maybe he'd even be able to influence the early development of the Hidden Leaf Village in ways that would make it stronger in his own time.
Naruto would meet his younger self. This would be a really strange situation. He could also meet all the important shinobi from the past. For example, the First and Second Hokage. He might have a chance to learn from them directly, instead of just hearing about them in stories. Additionally, he could meet some of the characters who were only mentioned in passing in the original story but had a big influence in the past.
In such a fanfiction, Naruto might try to prevent some of the tragedies that occurred in the past. For example, he could stop the Uchiha massacre. He would use his knowledge from the future to change things. Maybe he'd also be able to save some characters who died early in the original story, like Jiraiya. And he could potentially have a huge impact on the relationships between different clans, as he'd know about future conflicts.
Naruto's character might develop a greater sense of responsibility as he realizes the impact of his actions in the past on the future. He may become more patient, knowing that he has to tread carefully to avoid major disruptions.
Jiraiya. Naruto could have a different kind of apprenticeship with Jiraiya. He could share some of his future experiences with Jiraiya, which might change how Jiraiya trains him and also how Jiraiya approaches his own missions and prophecies.
One interesting plot could be Naruto using his future knowledge to prevent the Uchiha massacre. He might try to change Itachi's situation and find a way to resolve the conflict between the Uchiha clan and the village without all that bloodshed.
One interesting plot point could be Naruto using his future knowledge to prevent certain tragedies in the past. For example, he might stop the death of a beloved character. Another could be his interactions with his younger self and how he imparts wisdom without revealing too much.
Naruto's character could develop in many different ways. If he travels to the past, he'd have to adapt to the different ways of the old ninja world. He might become more respectful of the traditions as he sees how they were formed. Also, he could become more of a mentor figure to the younger versions of his friends, which would change his self - perception from a student to a teacher, thus making him more mature and responsible.
The main character, Fan Xian, had transmigrated into the television series, Celebrating the Year. In the play, Fan Xian was a modern youth with myalgia gravis. When he woke up, he found that he had become a baby and had arrived in the ancient world of Qing Yu Nian. He started a series of adventures and battles in this world, living with the help of the killing system. Fan Xian's time travel was not a traditional time travel drama, but a sci-fi plot. This world was a future society that had revived after human civilization was frozen. Thus, the main character Fan Xian had transmigrated to Qing Yuannian, a society rebuilt after the end of the human world.
There were a few novels that transmigrated to the world of the celebration. Among them were "I'm a Fan in the Year of Celebration","The Killing System of the Year of Celebration","The Invincible Beginning of the Year of Celebration","The Journey of Little White in the Year of Celebration","I'm the Main Character in the Year of Celebration (You're a Transmigrator)","Reincarnation begins from the Year of Celebration (You're a Transmigrator)","I'm a Group Pet in the World of the Year of Celebration","A New Life Begins from the Year of Celebration", and "The Beginning of the Year of Celebration". These novels were all set in the world of the New Year and described the adventures and experiences of the protagonist in this world.