Actually, I already know why most people claim "Jesus"
existed. They do it on the basis of the popularity of the belief in it, as well as
non-contemporary, non-credible, contradictory sources like the Gospels and
Josephus.

So your position is apparently that the Encyclopedia Britannica and other such reference texts consist mostly of non-controversial well-justified assertions, but also the unjustified assertion that Jesus was historical. What other assertions in such reference texts do you consider to be unjustified?  If none, then how do you explain that the professional scholarly consensus is wrong on just this one topic that just happens to be so personally important to you? Might it not be the case that your personal emotional investment in the ahistoricity of Jesus has led you to a biased assessment of the evidence?

I treat Jesus ahistoricity the way I treat creationism. When a theory is so at odds with the scholarly consensus, I don't bother debating whether the consensus is true. Instead I debate why the consensus would be wrong on this one topic and not others. If you can't explain this alleged anomaly, then I assume that what's anomalous is your assessment of the consensus and not the consensus itself.