No, the "Sons of Seth" explanation is nonsense. Book of Enoch actually explains in great detail who these were. So, part of the problem has been, if these were fallen angels, since angels are pure spirit, how can they lust after human females and then assume bodies to mate with them?
So, I posit an intermediate type of angel, a missing link, as it were, in God's hierarchy of creation. In addition to angel, human, animal ... between human and angel you have the lowest tier of angel who, like humans, have a "sensible part" of their soul, but unlike humans, do not require having bodies of their essence, but where they can assume bodies ... not just animate them like puppets or possess them, but where they can fashion bodies for themselves out of inert matter, or earth, as they will, and have these bodies interface from that sensible part of their soul into the material world. Technically speaking, PURE spirits should not be able to interact with the material world. We have the example of those men who visited Abraham and ate with him ... but they ended up being angels. How do angels eat? Just a trick or an illusion? Did they find a few humans to possess? Pure angels, even if they assumed bodies, could not actually taste the food they were going wrong, since they would have no sensible part of their souls to which the density information could be common to their spirit.
Judgment on False Teachers
5Now I desire to remind you, though you are fully informed, that the Lord, who once for all saved[g (https://biblehub.com/nrsvce/jude/1.htm#fen)]a people out of the land of Egypt, afterward destroyed those who did not believe. 6And the angels who did not keep their own position, but left their proper dwelling, he has kept in eternal chains in deepest darkness for the judgment of the great day. 7Likewise, Sodom and Gomorrah and the surrounding cities, which, in the same manner as they, indulged in sɛҳuąƖ immorality and pursued unnatural lust,[h (https://biblehub.com/nrsvce/jude/1.htm#fen)] serve as an example by undergoing a punishment of eternal fire.
8Yet in the same way these dreamers also defile the flesh, reject authority, and slander the glorious ones.[i (https://biblehub.com/nrsvce/jude/1.htm#fen)] 9But when the archangel Michael contended with the devil and disputed about the body of Moses, he did not dare to bring a condemnation of slander[j (https://biblehub.com/nrsvce/jude/1.htm#fen)] against him, but said, “The Lord rebuke you!” 10But these people slander whatever they do not understand, and they are destroyed by those things that, like irrational animals, they know by instinct. 11Woe to them! For they go the way of Cain, and abandon themselves to Balaam’s error for the sake of gain, and perish in Korah’s rebellion. 12These are blemishes[k (https://biblehub.com/nrsvce/jude/1.htm#fen)] on your love-feasts, while they feast with you without fear, feeding themselves.[l (https://biblehub.com/nrsvce/jude/1.htm#fen)] They are waterless clouds carried along by the winds; autumn trees without fruit, twice dead, uprooted; 13wild waves of the sea, casting up the foam of their own shame; wandering stars, for whom the deepest darkness has been reserved forever.
14It was also about these that Enoch, in the seventh generation from Adam, prophesied, saying, “See, the Lord is coming[m (https://biblehub.com/nrsvce/jude/1.htm#fen)] with ten thousands of his holy ones, 15to execute judgment on all, and to convict everyone of all the deeds of ungodliness that they have committed in such an ungodly way, and of all the harsh things that ungodly sinners have spoken against him.” 16These are grumblers and malcontents; they indulge their own lusts; they are bombastic in speech, flattering people to their own advantage.