Then the life of Superman in the Superman comics prove the existence, basic goodness, and superhumanity of Superman. The existence of a book about something does not prove the existence of someone, nor that the book accurately portrays that person or thing even if he/she/it did or does exist.

Further, the existence of a claim (as the Bible makes the claim of "Jesus is divine") cannot be used as evidence of that claim, or a broader one (divinity exists), evidence outside the claim must be introduced. Those who wrote the Bible had a self-interest in promoting their beliefs (every possible motivation from money to social and political acceptance) and thus the Bible should not be viewed as an unbiased source.