There are partial copies dated as far back as early 100s. References are in the 50s to 60s. Luke did write an investigative report and Mark may have written from Peter or other first hand sources. 3rd person Jewish
Writing was common.
John was in his 90s and he was inspired to do so perhaps to provide additional documentation. God saved His people who accept such a lifeline by taking their form and taking their punishment. It doesn’t make sense to us because we are not perfect and no longer have a perfect love for anyone or anything. We would not do this. But He did because He loves us.
That wasn’t what I mean. The idea of saving one, let alone all, when they deserve punishment instead, is a perfect love. Mankind loves but it’s not perfect all of the time