I doubt that you will believe the answer that I am about to give but you said you wanted proof:
There are 22 “I AM” Sayings in the book of John that Jesus declares himself to be the same God as was revealed to Moses in the burning bush - “I AM THAT I AM”
1. Jn 4:26 Jesus said to her, "I AM the One speaking to you"
2. Jn 6:20 But He said to them, I AM! Do not fear.
3. Jn 6:35 Jesus said to then, I AM the Bread of the Life
4. Jn 6:42 Then the Jews murmured about Him, because He said, I AM the Bread coming down out of Heaven.
5. Jn 6:51 I AM the Bread that came down from Heaven.
6. Jn 8:18 I AM the One witnessing concerning Myself.
7. Jn 8:23 And He said to them, You are from below; I AM from above
8. Jn 8:24 Therefore, I said to you that you will die in your sins, if you do not believe that I AM, you will die in your sins.
9. Jn 8:28 Then Jesus said to them, When you lift up the Son of Man, then you will know that I AM; and from Myself do nothing; but as My Father taught Me,
10. Jn 8:58 Jesus said to them, Truly, truly, I say to you, Before Abraham came into being, I AM
11. Jn 9:7 Then Jesus again said to them, Truly, truly, I say to you that I AM the Door of the Sheep.
12. Jn 9:9 I AM the Door, if anyone enters through Me, he will be saved, and will go in and will go out and find pasture.
13. Jn 9:11 I AM the Good Shepherd!
14. Jn 9:14 I AM the Good Shepherd and I know those that are Mine; and I am known by those that are Mine.
15. Jn 11:25 Jesus said to her,I AM the Resurrection and the Life, the one believing into Me, though he die, he shall live.
16. Jn 12:19 From this time I tell you before it happens, that when it happens you may believe that I AM.
17. Jn 13:6 Jesus said to him, I AM the Way, and the Truth and the Life.
18. Jn 15:1 I AM the True Vine, and My Father is the Vine-dresser.
19. Jn 16:5 I AM the Vine you are the branches.
20. Jn 18:5 They answered Him, Jesus the Nazarene. Jesus said to them I AM!
21. Jn 18:6 Then when He said to them, I AM, they departed into the rear and fell to the ground.
22. Jn 18:8 Jesus answered, I told you that I AM; then if you seek Me allow these to depart,
Now about your statement that the bible was written decades after Jesus' death, that is misnomer, all the Old Testament had been written comprising a 1800 year period. And the books that were earlier if you knew anything about culture and archeology was that most of ancient history was oral and passed down as oral history, this oral history has been proven by archeologists to have been very precise history, now about the New Testament none of the books were written because most of the eye witness and the apostles were still alive decades afterwards, the first gospel mark was written in the early 40's at best, then possibly Luke then Matthew and then John's in the early 90's so generally the epistles of Paul were penned generally before or at the same time as Matthew and Luke especially because Luke followed Paul on his many travels, - now about this emperor changing the bilbe - well you can believe it if you want to - because gives you a way not to believe and obey the Word of God - you will be held accountable anyway!