(This theme is surely past its ‘use by’ date, but it’s one I’m working through from a number of angles at the moment, so here goes once more.)
While it is often said that there is as much, even more, evidence for Jesus than for other ancient historical figures, this is simply not true.
Historical Evidence for Alexander and Julius Caesar
For Alexander the Great we have coins and other epigraphy as primary evidence. We also have a number of mythical narratives of Alexander. But the primary evidence testifies to his real existence nonetheless. With that primary evidence in mind, we can have confidence that not all literature about Alexander is necessarily fictional. I have compared the character of the five historical accounts of Alexander with the Gospels in an earlier post, Comparing the Sources for Alexander and Jesus.
For Julius Caesar, we also have coins and monuments with relevant epigraphy. There are many literary works that attest to be by contemporaries of Caesar (and that refer to Caesar), such as Cicero, and even works claiming to be by Caesar himself. I don’t think these are forgeries, but even if they were, the primary evidence alone would keep Julius Caesar “real”. That is before we even get to ancient historical works proper about him (Plutarch, Cassius Dio, Suetonius, Arrian).