What are your starting assumptions? What would you expect to find if Jesus did exist, and why? What is your basis for comparison with respect to our evidence for Jesus and other figures from ancient history?
Here, for example, is a paper I wrote as an undergrad on the historical Socrates, which not only compares reconstructing the historical Socrates and the historical Jesus, but covers the history of both (albeit briefly, as the paper itself without footnotes or the reference section is only 35+ pages):
The Quest for the Historical Socrates
If we had no gospels and only the letters of Paul, the one unquestioned reference to Jesus in Josephus (which simply uses Jesus to identify his brother James), and Tacitus, we'd have more evidence for a historical Jesus than we do for Pythagoras. We'd know next to nothing about him, of course, but that's true of most of the people we know of from ancient history. The mere fact that a contemporary of Jesus knew Jesus' brother, who is also identified as such by Josephus (a non-christian historian who was around when Jesus' brother was executed), would provide a contemporary witness to a family member of Jesus and backed up by a very early secondary source. That's quite a lot, given that for many names which survive in the ancient record we can't be certain which one is which (how many Antiphon's were there), or all the information we have comes from at least a century after the person lived, or it's just a name in a letter which we can't know was accurately perserved because the manuscript or two we have dates from the middle ages. And that's without factoring in other non-gospel sources like Papias, who states that he didn't care what his fellow christians had to say about commandments unless they could report what those who knew Jesus (he ends his list with "any of the lord's disciples" but specifically mentions Andrew, Peter, Philip, Thomas, Matthew, James, John, the elder John, & Aristion) said about Jesus' teachings. Other non-christian sources are covered in brief (with plenty of references) in Theißen and Merz'
Der historische Jesus in section 3 "Die nicht-christlichen Quellen über Jesus" from Josephus to Thallus.
However, we DO have the gospels. They are biased, they are religiously motivated, they contain so much doesn't belong in modern history, but they aren't "modern history." They are ancient histories, and such works existed along a continuum from the more careful and skeptical to the much less so. Ancient Greek and Roman historians from Herodotus onwards used sources like the
Iliad in their work, including Polybius, Diodorus Siculous, Livy, etc. Caesar reported unicorns in Germania. Philostratus wrote a biography of the magician Apollonius. Dionysius rejects the myth that Romulus and Remus' mother was impregnated by a god, because that's just obviously unbelievable, so he concludes that she was raped. The fact that the entire basis for her existence was pure ancient legend didn't seem to occur to him.
Then there's the fact that even blatantly and deliberately non-historical genres discuss historical individuals. Aristophanes' comic plays on Socrates are a prime example. Paul is another: he was writing letters. We know a great deal about letters, how they were written, what formulae they followed, etc., in and around Paul's day. Written speeches by professional orators are another.
In short, there's no good reason to reject the gospels as completely unreliable sources for Jesus. They are early, they are a type of ancient history, they represent independent traditions (most likely, Mark, Q, and John, and perhaps Matthew and Luke had independent sources apart from Mark and Q). The brother of Jesus mentioned by Paul and Josephus is independently attested to in Mark and Q. Not only that, but these documents were preserved like no others in history. Apart from the possible recent 1st century finding of a scrap of Mark, our earliest papyrus is from John, the last gospel, and was written not long after the original. When I read editions of Euripides, Plato, Xenophon, etc., the textual critical apparati would mention a few manuscripts, because that's all we had (and I didn't realize until later that most of these were written over a thousand years after the original). Yet the gospels and Paul's letters were copied and distributed widely and early, while people like Josephus (and even older individuals) were still around. So why, if Jesus never existed, but there is so much evidence which dates from periods while his alleged followers and even family were still alive, did no one question his existence? We're talking about a highly communal (non-individualistic) society where family and kinship are everything and such networks are quite wide. The idea that just Mark alone, which situates Jesus in a recent time and in particular places, could be widely distributed by followers without anybody realizing that Jesus didn't exist, that his disciples either didn't exist or were lying about his existence (and the same with his family), is baseless.
That an individual could gain followers and be thought to perform miracles by those around him is absolutely believable. It happens today (with "faith healings" and other "miracles" or magic).
What 3 volume series? And can you read greek or latin? That becomes quite important, for everything from understanding genre to understanding why a particular phrase or line (such as those referencing Jesus' brother) ought to be read in a certain light. What secondary scholarship have you read on greco-roman historiography? Or textual criticism? If you've read Josephus and Vermes, what do you think of Vermes' analysis of the so-called
Testimonium Flavianum?
Again, why would I read non-academic works which are quite outdated? They have less access to information than I have, both concerning primary sources and secondary.