What is your historical proof that claiming to be an agent of God is considered blasphemy? Are prophets, kings and priests not agents of God to the children of Israel? I don't know of anyone accused of blasphemy for so doing.
Also, sounds like you are implying Jesus blasphemy was claiming to be God's agent yet the high priest somehow thought this claim to be God's agent is a claim to divine authority yet the Son of Man is not a divine figure according to you? Can you make that make sense please? Isn't this self refuting?
This "powerful but not divine (according to you)" Son of Man stands in the presence of God, is given eternal dominion and glory and EVERYONE is supposed to worship Him. How do you reconcile this with the command of God to have no other God before Him if there is another eternal being who He authorises the nations to worship forever and ever?
And going with your claim, what kind of powerful being exactly would Jesus have had to claim to be in order to threaten the existing religious system? One that perhaps rides the clouds like God does and is worship like God is?
Secondly, Jesus was worshipped and prayed to as God in the book of Acts which is pretty much straight after His ascension so to say it developed decades later is highly inaccurate.
Finally, no, if everyone around Jesus (disciples and enemies) got the same unequivocal message, with Thomas calling Him God and Jesus in response calling that faith, the onus is on the 21st century chap thousands of years removed from the events and culture to make the case why the eyewitnesses themselves and 2000 years of church tradition have misconstrued Jesus...and saying he never said "I am God" when He calls Himself the First and the Last, I AM, LORD, Good Shepherd, Truth, the Almighty and a host of other divine names exclusive to God, is a playground argument my friend.