The canon has included only those books which are inspired and there are no other books equivalent or near equal.
Why only these are considered inspired?
If God were to authenticate any of the books as His communication and therefore as inspired teachings, He would have to verify it in a manner that could not be duplicated by mere humans. Otherwise people could make up their own messages and simply claim that they came from God. God achieved this by fulfilling of many prophesies recorded in these books over the ages.
The real determination of any books claim for its inspired truth is in its supernatural evidence, including prophecy. God used prophets to speak and write down His Word and God used miracles like fulfilled prophecy to authenticate His messengers. For example, in Genesis 12:7, God promises the land of Israel for Abraham and his descendants. In 1948 Israel was returned back to the Jewish people for the second time in history. This may not seem so astonishing until you realize that no nation in the history of the world has been scattered from its homeland and returned! Israel has done it twice. The book of Daniel predicts with accuracy the coming of the four great kingdoms from Babylon, to Medo-Persia, to Greece, to Rome centuries before some of those kingdoms came on the scene (a time span of over 1,000 years!) with details concerning how they would rule and be broken. This includes the reigns of Alexander the Great and Antiochus Epiphanies.
In the book of Ezekiel 26 we can see in astonishing detail how the city of Tyre was to be destroyed, how it would be torn down, and how its debris would be thrown into the sea. When Alexander the Great marched on that area, he used these rocks, the leftover rubble from the city of Tyre for the land bridge.
There are several prophecies concerning Christ in the books of Old Testament and it would take more than a few screens worth of space to list them all. Further, Jesus would have had no control over many of them such as His birthplace or time and type of birth. Second, the odds of one man accidentally fulfilling even a very few of these is miniscule.
There are other books (after canonization of Bible) claiming to be inspired but they make clear historical and judgemental errors. Others have no fulfilled prophesies to claim that they are inspired. There are these other books which makes judgments against Christians for believing things that they do not (nor have they ever) believed. For example, there claims that Christians believe the Trinity is the Father, the Mother (Mary). Divinely inspired books need at least be able to accurately report what is being believed by others.