The ancient Bible thing is literally irrelevant and has nothing to do with the proof of Jesus existing. Several manuscripts here and there do not mean much overall.

Julius Caesar died before Jesus was born so that has no bearing on anything.

In Book 20, Chapter 9 of the Antiquities, Josephus mentions “the brother of Jesus, who was called Christ, whose name was James.”

Secondly, in Book 18, Chapter 5 of the Antiquities, Josephus mentions the imprisonment and execution of John the Baptist, who was Jesus’ cousin.

In Book 15, Chapter 44 of the Annals, Tacitus refers to the execution of Christ by Pontius Pilate.

These are clear evidences for the existence of Jeuss himself.