The ignorance of this response is rather bleak. I suppose part of the reason is by "trinity" being in the discussion here -- maybe not the fault of amazing grace, though. We mainly see the two here.Yes, God is the Father and Jesus is the Son. My thoughts on why logos was used in John 1:1 is because God's word did the creating in the beginning.
The question would be - What would the original readers have understood with this verse? We have to remember that this was written to people who had NO IDEA OF AN ESTABLISHED DOCTRINE OF THE TRINITY. They only had what was known through the OT scripture and scripture clearly depicts that a singular person identified as either the LORD, the LORD God, or God - created.
I did not respond to any of the above.
It is far too weak to say they only had the OT here. Of course they already have many of the NT writings. And most of the people reading the gospel likely were gentiles. Also, there were the Greek philosophers and Philo who had influenced people despite being inspired who thus were not all accurate. Yet, they were influential.
Furthermore, there has been the knowledge of Christ Jesus. That is why many people read it. That is why they could know details ahead of reading this. John is not speaking out of the blue. He is writing in light of all this earlier information. He however adds insights in John 1:1 and continues about the deity of Christ. You seem unable to get beyond the Pharisaical understanding (or even ignorance) and thus join into the NT knowledge.