I trust the God has preserved His word as He wants us to have it today.
>> For instance why isn't the Book of Enoch or the Gospel of Thomas included?<<
Sayings in The Gospel of Thomas attributed to Jesus run counter to what is written in the four Gospels and the gospel of Thomas was not written by Jesus' disciple Thomas. The Book of Enoch has to many contradiction to what the apostles wrote.
Did you diligently research and study those books and come to that conclusion on your own, or did you rely on the work of other people and accept their conclusions?