Who are the "we" and "I" at the end of the gospel of John?

Question

The gospel of John ends with (NIV) John 21:

20 Peter turned and saw the disciple whom Jesus loved following them.

As usual in this book, Apostle John refers to himself as "the disciple whom Jesus loved" in 3rd person singular:

He was the one who had leaned back against Jesus at the supper to ask, “Lord, who is going to betray You?”

24 This is the disciple who testifies to these things and who has written them down.

The author has just identified himself.

And we know that his testimony is true.

Who are the "we"?

25 There are many more things that Jesus did. If all of them were written down, I suppose that not even the world itself would have space for the books that would be written.

Who is this "I"? If this refers to Apostle John, this is the first and the last time, the author used the first person singular to refer to himself.

Related questions:

Does John 21:20-24 indicate that the original author of the Fourth Gospel was dead?
Was the Beloved Disciple the author of the Fourth Gospel?
Who was the Beloved Disciple?
I assume Apostle John is the author.

Answer 1

Who are the "we" and "I" at the end of the gospel of John?

And we know that his testimony is true. "We" by this John refers to his fellow apostles.

Who knows of "his testimony", John opens the prologue to his letter with delight, Jesus other Apostles have also seen and heard him speak, and saw the miracles that he performed, John says;

1 John 1:1-4 NET

1 This is what we proclaim to you:[a] what was from the beginning,[b] what we have heard, what we have seen with our eyes, what we have looked at and our hands have touched (concerning the word of life— 2 and the life was revealed, and we have seen and testify and announce[c] to you the eternal life that was with the Father and was revealed to us).[d] 3 What we have seen and heard we announce[e] to you too, so that[f] you may have fellowship[g] with us (and indeed our fellowship is with the Father and with his Son Jesus Christ). 4 Thus[h] we are writing these things so that our joy may be complete.

Who is this "I"? This refers to Apostle John,

5 There are many more things that Jesus did. If all of them were written down, I suppose that not even the world itself would have space for the books that would be written.

John says that there were many other things that Jesus did, John did not try to write it all but wrote enough and with all that was already written, prove conclusively that Jesus Christ is the Son of God:

John 20:30-31 NASB

30 So then, many other signs Jesus also performed in the presence of the disciples, which are not written in this book; 31 but these have been written so that you may believe that Jesus is the [b]Christ, the Son of God; and that by believing you may have life in His name.