Kakashi could also play a role. He has always been a mentor to Naruto and his sense of duty and loyalty to his student might drive him to search for Naruto when he hears that he's been left for dead. He has the skills and knowledge to find and save Naruto in a difficult situation.
Iruka Sensei could also be a candidate. He was one of Naruto's first supporters and has a deep connection with him. He would probably risk a lot to save Naruto.
A new character could be an old friend of Naruto's parents who shows up. They might have some information about his family and why he was left behind. Maybe there's a healer who tries to help Naruto deal with the emotional scars of being left behind. This healer could have their own backstory related to loss and abandonment as well.
It could be a rogue ninja from another village who has a vendetta against Naruto. This ninja might have set a very elaborate trap that made it seem like Naruto was killed and left his body in a place where his friends would find him and think he was dead.
He might survive through his own sheer willpower. Naruto has always been a tenacious character. So, even when left for dead, his determination to live and achieve his dreams could keep him alive against all odds.
One consequence could be that it makes him an outcast. Controlling the dead is often seen as a dark and forbidden art, so his friends and allies might be afraid of him or turn against him.
Some less obvious choices could be Kurenai. Her experience and calm nature could contrast well with Naruto's more energetic personality. Also, Konan could be included. Her skills and backstory could make for an interesting relationship with Naruto within the context of a harem, and she has a certain allure that would fit in well.
Initially, Naruto could be filled with anger. He might feel like all his efforts to protect the village and be accepted were in vain. However, his strong will and belief in himself would likely kick in. He could decide to train even harder, not just to prove his innocence but also to become strong enough to face whatever force was behind his betrayal. He might also start to question the values of the village he once held so dear.
Kakashi could be another important character. As a mentor figure, he might be guiding the younger generation through the difficult times after Naruto's death, using his experience and wisdom to keep the village stable.
Maybe a mysterious ninja from a hidden clan shows up. This ninja is intrigued by Naruto's situation of being left behind by Sakura and decides to help him. They could have some really cool powers like the ability to manipulate shadows in a different way than the Nara clan. Also, there could be a healer from a neighboring village who comes to Konoha. She helps Naruto deal with his emotional wounds from being left behind, and in the process, they become good friends.
One possible reason could be a misunderstanding. Maybe they were misled by false information or an enemy's trickery that made them think Naruto was a threat at that moment. Another reason might be extreme pressure or a life - or - death situation where they thought sacrificing Naruto was the only way to save the rest of the team or complete a crucial mission.