This is really a non argument, and I seriously advice stopping to waste any of your time on this argument.

There are some non christian sources displaying Jesus but that is not the case I wish to make.

If you are going to use this argument to say that my viewpoint is wrong and unfounded, I have this argument for you

"Prove to me Adam existed. He lived for more than 900 years, surely you have some evidence of his existance?"

"You can't? Hmmm, so this means your faith is errournous because one of your main characters did not exist. He should have left some evidence in 900 years shouldn't he have? build some cities or something? they seemed fond of doing that. Plus he was famous because he was widely known as father of all men for 900 years... people could visit him and question him about God...
but, since you can't prove he existed, he musnt have existed, so this also means the book of genesis is wrong. No-one is a sinner, because the rebellious nature is not inhereted as is displayed in genesis 5.
To bad, you're following a mythical faith with a non existant God"

I do hope you see how much of a non argument this argument is, and I do hope you don't waste any more time on this, otherwise you have to also admit the above argument, that your faith is not valid either.

Shalom Aleichem,

Michael