Wasn't Namikaze Minato dead? Why was he resurrected again in more than 500 episodes?

Ultimate Earth Reincarnation

A technique in the Japanese anime "Naruto". A forbidden psychic technique created by the second generation Hokage Senju Tobirama. This technique can summon the souls of long-dead ninjas back to the human world and resurrect them in physical form. The resurrected person can be controlled by the caster. However, the caster can release the control. In addition, if the person being cast knows the seal of the Reincarnation of the Reincarnation, he can actively cancel the Reincarnation Contract of the Reincarnation. It is worth mentioning that the Six Paths Sage can directly unlock the Earth Reincarnation Ninjutsu even if he is not a caster.