I don’t believe that Moses wrote Psalm 90 because it states that our lives are threescore and ten. At the time of Moses, the lifespan was about 120 years not 70 years. Another mistake by man though the devil's guidance.
John 21:24-25 is clearly that John was not the author of this passage and @DickHarfield answer above kind of summarises it so I will not repeat what has been said. Especially when words like we are used and you have other passages like;
One of them, the disciple whom Jesus loved, was reclining next to him. [John 13:23]
Was this just a 'post scriptum' by ...
The Gospel of John concludes already in 20:30
Jesus performed many other signs in the presence of His disciples, which are not written in this book. 31But these are written so that you may believee that Jesus is the Christ, the Son of God, and that by believing you may have life in His name.
I am not the first one to observe that chapter 21 is a post ...