Doesn't matter. Using the stereotypical white Jesus image allowed the point to be conveyed without having to explicitly spell out that it was Jesus. And looky, you understood it just fine.
The odds are Jesus wasn't white, but he wasn't black, Asian, or middle Eastern either. He most likely didn't exist, and having some empty space saying reboot your computers isn't as funny.
Historians agree that someone named Jesus of Nazareth lived at that time, and was doing some preaching, and started a new religion. What they don't agree on is all the mythical stuff, miracles and the like. It's very likely, given the demographics at the time, that he was middle-eastern or what we would consider "Persian" for about 1000 years.
Many historians agree that some time after 0CE people wrote about someone named Jesus, but almost solely written by people who didn't directly encounter Jesus, so basically hearsay from 2000 years ago.
Other historians don't think Jesus existed at all.
Most of the "evidence" is the Bible, which doesn't really count. Other evidence is from 50-200 years after his supposed existence.