Why did Obito fight Minato in Naruto? He was still a child when he was Kakashi's disciple. Did he travel through time and space?

According to the comics, Obito lost half of his body at that time (was crushed by a stone), and Madara used the first-generation cells to make half of his body, but it was not very good. As long as he exercised strenuously, he could still It will be ruined... Later, before Obito opened his eyes, he had to find Kakashi, who had difficulty moving, and Uzumaki (a guy who is the same as White Zetsu, but his face is like Obito's mask, which is a whirlpool) Wrapped his body, Obito's body became like an adult. After the Sharingan opened, Obito was able to use this body, and he appeared in this form later... As for the ninjutsu in that space, it was Professor Madara...