"Why did Jesus (supposedly) die for us?" ...to convince a population of skeptical Roman Pagans that it was in their best interests to join Emperor Constantine's new "universal" religion. When that didn't work, Augustine of Hippo devised Original Sin and the concept of the human soul, which was claimed to be a bit of God's own immortal being, which he loaned to each person at the moment of their birth. (This was changed to the moment of conception during the mid-twentieth century, to justify the Church's opposition to birth control.)
The idea that Jesus died to save us from His Father's Divine wrath is superstitious nonsense, based on the Platonic idea that both human minds and the gods themselves dwell in an ethereal place free of physical objects, which the Catholics eventually called Heaven.