A theological possibility is the pre-incarnate Jesus might have been who appears when Jacob wrestled the angel. It's also.plausible that Melchezideck is a pre-incarnate Christic figure.

We know that angels can take the form of humans but don't necessarily look like them whatsoever, and that inspired fear all throughout the Old Testament. Demons being fallen angels would have that same origin.

Lucifer as the great dragon may stem from the root to the serephim from the Hebrew saraph meaning serpent-like, either as being as swift a serpent or as poisonous ie causing a burning pain like a serpent's poison.

We don't know definitely, but this is what is parodied today and is rooted in depictions and influenced Baphomet and linked to the ridicule of the left hand path which draws the goats who are rejected by Jesus in the parable of the sheep (right) and the goats (left).