In Deuteronomy 15:11, this signifies that truth requires good and good truth, and always will. (Arcana Coelestia 5365)

In Psalm 21:5, this signifies that the Lord will to eternity deliver those deprived of truths and good against their will. (The Inner Meaning of the Prophets and Psalms 271, Apocalypse Explained 95)

28. The reason “the Son of Humanity” means the Lord as the Word was that the prophets were also called “children of humanity.” The reason they were called this is that they represented the Lord as the Word and therefore meant the teaching of the church drawn from the Word. That is exactly what people in heaven understand by “prophets” when they are mentioned in the Word. The spiritual meaning of “prophet” and also of “son of humanity” is the teaching of the church drawn from the Word, and when it is said of the Lord, it means the Word itself.

For the prophet Daniel being called a son of humanity, see Daniel 8:17.

For the prophet Ezekiel being called a son of humanity, see Ezekiel 2:1, 3, 6, 8; 3:1, 3-4, 10, 17, 25; 4:1, 16; 5:1; 6:2; 7:2; 8:5-6, 8, 12, 15; 11:2, 4, 15; 12:2-3, 9, 18, 27; 13:2, 17; 14:3, 13; 15:2; 16:2; 17:2; 20:3-4, 27, 46; 21:2, 6, 9, 12, 14, 19, 28; 22:18, 24; 23:2, 36; 24:2, 16, 25; 25:2; 26:2; 27:2; 28:2, 12, 21; 29:2, 18; 30:2, 21; 31:2; 32:2, 18; 33:2, 7, 10, 12, 24, 30; 34:2; 35:2; 36:1, 17; 37:3, 9, 11, 16; 38:2, 14; 39:1, 17; 40:4; 43:7, 10, 18; 44:5.

We can see from this that the Lord as the Divine-Human One is called “the Son of God, ” and as the Word is called “the Son of Humanity.”