I think you are holding the historicity of Jesus Christ to an impossible standard, one not required of many pagans who are widely accepted as historical figures. You further make claims, not substantiated, as to when the Gospels were written and by whom. For example, the book of John was recorded by one who knew Jesus intimately, and Luke's Gospel was carefully constructed from those who were eyewitnesses, meaning the writer spoke to those with personal first-hand knowledge of the events, not "third-hand", as you claim. (John 21:24, Luke 1:1-3)
I don't know what "pagans" have to do with anything. Are you thinking of someone in particular? In any case, I'd be very careful about uncritically accepting biographical details about many ancient writers whose own works we have, and Jesus did not leave us any written works of his own. Recall that I accept his existence but draw a distinction between Jesus the man who lived back then and Jesus the character that is depicted in the Gospels.
I don't have the time or space or inclination to get into the evidence for the chronology of the Gospels, but really I shouldn't have to: nothing I said is remotely controversial in the academic realm. The belief that the Gospels were written by people with first-hand knowledge of Jesus, such as the disciples whose names they bear, has been thoroughly discredited and is not supported by any actual scholars at this point.
In fact,
John is generally agreed to be the latest of the four canonical Gospels (the tail end of the 1st century), at least in the form that we have, though it shows signs of at least one redaction and is thought to have been composed in stages, probably by at least three different authors over a number of years. Is there a significantly earlier strand within
John? Maybe. But it's a long way from acknowledging that to finding evidence of any sort of first- or even second-hand historical knowledge.
Luke may well have been written by Luke the disciple of Paul, and he's the one that emulates the Greek biographical genre most diligently, hence the apologetic preface. But if you're familiar with other examples of the genre (e.g. Plutarch, Suetonius) you'll know what that actually means, and it's not anything like modern historical standards of evidence. Did Luke have access to people who knew Jesus personally? It's not impossible--Paul claims to have met Peter and Jesus's brother James, although he apparently didn't get along with them--but that still doesn't mean a lot of
Luke the Gospel isn't a literary construct intended to further a particular theological program. As it is, Luke's main sources seem to have been
Mark and
Matthew, which isn't the same as going around and interviewing eyewitnesses.
And that's not to mention how the Gospels were clearly written by people with minimal knowledge of Jesus's life, but who are trying to construct one that they can hang what they
do know on. They have no idea when he was born, for example: the range of dates the canonical Gospels give (by saying what else was going on at the time) cover an entire decade. That's something you'd think his own brothers would have known, at least, if not his other immediate disciples. A lot of the scenes are clearly constructed in order to give context to sayings of his that were probably passed down as teachings rather than as the sort of narrative vignettes we get in the Gospels, which explains why they differ in details, as well as the sequence in which they occur. Even Jesus's trial, death, and resurrection are depicted in ways that are not mutually compatible, and which are in some cases patently ludicrous from the perspective of anyone who knows how Roman law worked.
And the original audience would have
known that. They would have
known that Caesar's census didn't require people to return to their birthplaces. They would have
known that there was no massacre of infants under the reign of Herod. They would have
known that people who were crucified were thrown into mass graves. But none of that was the point, since the point of the Gospels was never to recount facts. The point of the Gospels, like all ancient biographies, was to construct a meaningful characterization of their subject, using whatever details were convenient to support their program. Nobody who read works like those would have been unaware of or bothered by any of that. It's only modern people who insist on historical fact and literalism and on missing the forest for the trees.