You would need positive evidence for your claim, saying the biblical Jesus doesn’t exist in neither important nor mundane records does not prove anything.
And claiming that because the miracles aren’t mentioned in any records is evidence of a historical Jesus is also false.
What is commonly meant by the claim that a historical Jesus could exist, is that it would be entirely banale for a mundane historical Jesus to exist. Meaning we can’t disprove him, and so current best practice to assume he did, just like all the other Jeushas, Marks, and Petruses we never hear about.
That is however not proof a historical Jesus did exist, it is just the working assumption when we can’t possibly tell.
And the post here puts doubt on that assumption, as there has been proof that stories where attributed to the Jesus character, and he might only be as real as Superman or Kilroy.