Actually no it hasn't been proven the case, even non Christian scholarship acknowledges the historical existence of Jesus. Jesus is mentioned in the historical writings of Tacitus: The Annals of Imperial Rome, Luciens satirical attacks on Christianity, Pliny the Younger, Celsus, Suetonius all hostile sources who attack the divinity of Christ but none who dispute his existence. The only reason why the Jesus never existed argument gets any traction these days is because the events are so far in the past, at the time this argument against Christianity wasn't even an option. Not to mention the writings of the Church Fathers some who were taught directly by the apostles.