Loving the Messenger ﷺ more does not mean ceasing to love parents, children, or other people. Religion also places obligations toward them. The point is that revealed guidance takes priority when the wishes of someone dear conflict with what is right.
Example 1: A close friend asks you to assist in cheating. Refusing the wrongdoing can be both principled and genuinely caring.
Example 2: Serving parents, raising children responsibly, and treating relatives fairly are themselves part of prophetic guidance. Fulfilling these duties does not contradict love for the Messenger.
مِنْ وَالِدِهِ uses مِنْ in a comparison: “more than their parent.”