Why isn't the life-death-rebirth deity in Christianity original?

A life-death-rebirth deity, also known as a dying-and-rising or resurrection deity, is a god or goddess who is born, suffers death or a death-like experience, passes through a phase in the underworld among the dead, and is subsequently reborn, in either a literal or symbolic sense. Male examples include Asclepius, Orpheus, Mithras, Krishna, Osiris, Tammuz, Jesus, Zalmoxis, Dionysus, and Odin. Female examples are Inanna, also known as Ishtar, whose cult dates to 4000 BCE, and Persephone, the central figure of the Eleusinian Mysteries, whose cult may date to 1700 BCE as the unnamed goddess worshiped in Crete.