(These are some notes out of my journal, inspired by some recent reading and pondering.)
In view of the approach I’m taking in seeing a strong/high expectation of the Son of David specifically as Messiah, with some very elevated characteristics, notably supernatural ones as the Son of God, there is a necessity to look at or address the different core approaches in Christianity and Judaism.
I think it’s fairly clear that prior to the advent of our Lord there was a high expectation of the Messiah Son of David, especially elevated by the fall of the Hasmonean dynasty and the rise of Rome and their client-king Herod. (Perhaps the fall of the Hasmonean priestly kingship was seen as the equivalent to the end of direct Theocracy in the time of Samuel, with a Son of David to appear soon just as David followed Saul, a cypher for Herod.) And while this entailed a political kingship in the coming kind, it also entailed the supernatural healings, etc. The advent of Jesus was only partly satisfactory to those who expected the political/supernaturally-gifted Son of David, Son of God. The political aspect was completely unsatisfied, though the supernatural was satisfied. His own teachings, however, and statements about Himself, pointed away from the expected character and nature of the Son of David/Son of God. Rather than Son of God through descent from Adam as His firstborn son in creation/humanity, He was directly God the Son. This was a surprise to His disciples, and He lost many, who were expecting something and someone else.
In that regard, we have to see the choice of various “messiahs” by the Judeans and others in the first and early second centuries, most notably Bar Kokhba. It is likely that various of the leaders of Jewish factions in the First Revolt were also presenting themselves as messiahs, though this characterization is lacking explicitly in Josephus, who prefers Vespasian (!) as his messiah. [I think it likely that Josephus is the false prophet, and Berenike the whore of Babylon in the Apocalypse.] In any case, after Bar Kokhba and the banning of Jews from Jerusalem, major changes occurred in what must be called Rabbinic Judaism, the majority sect. It was undoubtedly at this point that an emphasis on the coming Messiah Son of David was stripped out of the tradition in order to prevent any further such disasters as the Bar Kokhba War and its consequences, after which the Messiah becomes such a pale character in Rabbinic traditions. Whatever earlier readings and interpretations and aggadot relating to this vividly expected Son of David therefore fell out of the tradition at this point. Concomitantly, a picture was lost of pre-Christian Messianic expectation, which would have largely overlapped with the readings incorporated in the NT (at the very least–I expect these were, in extent, similar to the body worked up in Patristic tradition, or at the very least built upon the same principles).
It is likeewise at this point, post Bar Kokhba, that the emphasis irrevocably moves from the Messiah Son of David as the Lawgiver and the source of judgments and so on to the conception of Oral Torah–a body that stands independently of every individual, but which is preserved and transmitted by the Rabbis, predicated now as originating at Sinai in an oral tradition rather than as the ad hoc rulings of the King who was righteous because of his having internalized the Law. This is another alteration. As Jesus in the Gospels is shown as one who is above the Law, this is reflective of the pre-Bar Kokhba royal understanding of the Messiah Son of David. This conception was not to survive in Rabbinic Judaism, and so is now considered something quite outrée, if not blasphemous. On the other hand, Christianity has maintained this older tradition of the Royal Law propounded by the King Messiah, Son of David, Son of God.