The author of the Gospel of John introduces himself at the end of the Gospel as the disciple whom Jesus loves, see John 21:24.
24This is the disciple which testifieth of these things, and wrote these things: and we know that his testimony is true.
Who is the "we" the author refers to? Himself? Even if that were the case, all you have is the author saying "I wrote these things --- I know my testimony is true.
Everyone testifying at any trial says "I know my testimony is true."
This disciple was present at the crucifixion, see John 19:26.
26When Jesus therefore saw his mother, and the disciple standing by, whom he loved, he saith unto his mother, Woman, behold thy son!
This verse, as all of "john's" verses, are written in the third person. Nowhere does the author say anything like; "
I heard Him say: "Woman, behold thy son!"
Also, who is the author referring to when he writes "...the disciple standing by"?
I asked you to show
evidence that the authors were actual eyewitnesses to the events. You have given none.
If I write a chapter in a book that says: "God, in the form of a butterfly, landed on my nose", you would have no reason to believe. Even if someone else wrote another chapter in the book and said: "God, in the form of a butterfly, landed on ecco's nose", I doubt you would consider these writing to be truthful.