Cofty your point about the identity of God and Jesus and their relationship is fundamental to Christian belief and yet as you point out it presents a striking ambiguity.
This fact is at the heart of Christian theology, for more than sixteen hundred years it has distracted the minds of honest people seeking truth but the father / son paradox presents us with the clear signature of something other than truth.
Only in myth can the irreconcilable be harmonized. Only in myth can contradictory, impossible or illogical tales be presented without an assault on the intellect.
I have been thinking about this for some time and conclude that the only answer is that the Biblical account is merely an extension and re-writing of older folk tales.
The oldest rustic wisdom comes from a vast repository of story-lines which gave the needed explanation for "the meaning of life" through the movements of the literal heavens as seen on a night with a clear sky. Humans always want an explanation.
Before writing was invented the description of the heavenly bodies served as the universal book and the tales of the heavenly gods were told again and again. They were drawn from the pattern of the constellations (formed only by the human imagination) and the daily rotation of the Earth and the annual movements of the Sun. Heavenly activity, it was thought, determined events on Earth in the form of natural effects of wind, storm, flood, drought, darkness, success or failure etc. Light and darkness were key indicators.
These tales transcend nation and continents and variants of them are to be found from Mexico to Siberia to India. The common factor being that the stellar objects are universal and the mnemonics for repeating their stories to the next generation became the foundations of universal religious belief.
This is a large subject deliberately hidden and condemned as pagan by fourth century Roman Christianity but to cut to the chase, the ambiguity of the father and son in the astronomical myth; is central to the solar myth element and is demonstrated at the spring equinox alias Easter.
The Solar hero “born in the Virgin” of astrology with oxen (Taurus) present, became the teacher and healer assembling his twelve helpers (zodiacal houses) as he travelled through them in the solar year. He was destined every year to be born on the shortest day and die a sacrificial death at Easter whereby he would as the Solar God return to his heavenly father who was also a Solar God. The two ruling together each year in heaven was explained by the increased strength of the sunlight in the northern hemisphere at this time of year.
Incidentally it was only from about 390 BCE that it was understood that the sun at Easter appeared to cross over or “passover” from the southern dominance to the northern. In technical speech the plane of the ecliptic i.e. the natural plane at which the centre of the Earth travels around the sun crosses over the line of the equator, making equal day and night time...which is the meaning of "equinox" and happens twice each year in spring and autumn. (It is necessary to have a clear mental image of why the seasons arise to grasp this.)
As the armillary sphere demonstrates this “pass over” forms a "cross" where the two lines converge (the plane of the ecliptic and the equator) and this saltire shape or St Andrews cross became the symbol on which the Saviour Mithra stood. So being sacrificed at the spring equinox on a cross was the mnemonic or symbol for the solar event. By this central belief we can connect the Jewish Passover with the Mithraic cross and all the solar- Gods such as Jesus, Dionysus, Attis, Osiris and Horus et al.
No self respecting saviour figure would be seen without his cross at Easter!
The confounding and persistent detail of the myth is that father of the sacrificed Solar God was himself a Sun God.