Why do atheists even bother about debating Jesus?

[Confused Ape]

The idea that Jesus wandered around Palestine preaching to people had to come from somewhere.

There is nothing new under the sun.

So dozens of people just woke up one morning believing that a man called Yĕhōšûă or Iēsous or Iesus had wandered around Palestine? If he was invented, somebody had to provide this fictional character with a name and some kind of background. Was the inventor a Jew or a Greek or a Roman? And why pick that name in particular?

Oxford Englisn Dictionary Definition Of Jesus

from Christian Latin Iesus, from Greek Iēsous, from a late Hebrew or Aramaic analogous formation based on Yĕhōšûă‘ 'Joshua'

What we really need is concrete proof for where the idea came from. I'm stuck for google keywords so perhaps you might be able to find something out for us.