We lost of LOT of information when the Library of Alexandria was destroyed. Unfortunately, most of the historians we have of the ancient world wrote centuries after the events they describe. For example, we have reports of people writing about Alexander the Great during his lifetime, but the earliest writer we *have* is from a couple centuries later. This is typical of ancient sources.<quoted text>
Josephus was born AFTER the supposed Biblical events. He could not have written first hand accounts of them. The best he could have done is to record the oral legends of the time (hearsay). You've still got nothing.
Almost no ancient historian held a firm line between legend and fact, though. Histories were often written as morality lessons for the young or as propaganda for the reigning power or for some political persona (Julius Caesar's writings were almost pure propaganda).
Josephus was not working solely from oral traditions. The Jewish people were literate and did record many events of their time. So Josephus was (often, not always) working from sources from the time he was writing about. He certainly was for the writings about later events.
For the most part, Josephus is considered a reliable historian, certainly better than, say, Herodotus. But like all ancient historians, he wrote for a political purpose and we have to understand his biases, distortions, and purpose in writing. We also have to understand that we don't have any *originals* of his writings, which means we often have to consider the biases of those who transcripted to give us the manuscripts we have today. In particular, the passages on Jesus are almost certainly later additions and not written by Josephus at all.