I’m fairly happy that your Kurios argument is nowhere near as strong as you assert. The problem is that there just isn’t enough evidence provided in scripture to demonstrate the distinction you take as a given: Jesus was delegated the attributes of YHWH rather than embodying them in himself as a person. Even if he had been delegated these attributes, the lack of due deference to YHWH rather than himself requires some much more searching questions about his identity than is provided in the simple narrative solution you are proposing.
I’m also fairly happy that the deductive argument about the divine identity of Jesus works. It can be demonstrated in the gospels, which were the product of the earliest Christian communities (well before the supposed Hellenistic Platonising of a later period) which worshipped Jesus as God, and seem to have had that agenda in the way Jesus is presented. If he wasn’t a divine figure, you have yet to address the more compelling question: who was Jesus?
The deductive argument also works with the term “Son of God”. The term had various meanings in the OT, of which Israel’s messiah was just one. Not only did Jesus fill YHWH’s character with unforeseen characteristics and how they should be reflected in his (Jesus’s) followers, but the same could be said of the developed meaning of the term “Son of God”. Clearly, if everything in the NT was limited strictly to whatever its meaning had been in the OT, then we would still be practitioners of the Law in its literal entirety, an enterprise whose impossibility would be giving us extreme problems. Jesus did not come to promote such a project, and neither should we in the larger issue of how we define Israel’s narrative.