I am sure there are eye witness accounts incorporated
Incorporated into what specifically?
and that's as good as it gets for much of any ancient history...in other words, good enough.
Good enough for what? Good enough for history books to talk about how Julius Caesar conquered Gaul and overthrew the Roman Republic...
... oh wait, bad example: we do have eye witness accounts for those events.
Historians gather the available evidence, evaluate it and draw conclusions based on its credibility and then write down their conclusions in books. By the way, the evaluation absolutely does include asking if it is contemporary and written by somebody who was there.
You don't have any accounts of Jesus' ministry from anybody who was there. You don't have eye witness accounts of his resurrection. You do have the fact that dead people don't come alive again. No neutral historian presented with that fact and the accounts of Paul and the Evangelists would conclude that Jesus did rise from the dead.
I think your disbelief of the accounts is due though to other factors based around the belief that these things just don't happen. More than if there aren't any signed witness statements I would imagine.
Dead people coming alive again just doesn't happen.
What the Epistles are are memos of a fairly sophisticated organisation established for a couple of decades whose members believe in a historical Jesus and that miracles and teaching occurred around him and their increased understanding of his divine connection and nature and that they are at least earnest in their beliefs.
Paul's genuine letters do not argue for a sophisticated organisation, if by sophistication you mean with a priestly hierarchy. However, I would agree that, by the time the books of the New Testament were all finished, there was a sophisticated Christian church. This is not evidence for miracles, only people's belief in miracles.
We have no problem with our recollections of the millenium. Why then start to think it was different for people in the first century?
I can remember exactly what I was doing on the night of 31st December 1999/Jan 1st 2000.
As it happens, I saw a man walk in his bare feet down the middle of the River Thames between London Bridge and Tower Bridge.
Also, on the same night, I watched the London fireworks from a twelfth floor flat in the Crystal Palace area.
There you are: you have an eye witness account to somebody walking on water. It must be true. Do you believe it? Do you believe my other account? Is there any reason to reject one and tentatively believe the other?
The thing is, before you even get to questions like that, you have to have an eye witness account and you don't have one for the resurrection of Jesus.