The Divine Tree and the Love Story
(My understanding of the drama)
The divine tree is like a gift from the heaven that can revive individual, giving chances to live again.
Because of Su Yi Shui love for Mu Qingge, he risked the torture of climbing up the heaven stairs to get this divine tree and giving up half of his power (half of golden core). Mu Qingge also gave him this tree of life as a symbol of somewhere to belong before? If the divine tree is a symbol of reviving and chances, she must have really wish him to live a new life and not someone born as demonic child because life can give us chances to lead the way we act on. Nothing is ever set in stone just as not everything of heavenly predictions are set correct.