A canon defines for a religious community what is authoritative literature, the divine word. The Hebrew Bible and Old Testament evolved over thousands of years until about 100 BC, and canonized even later when certain people decided which books to include and which to exclude.
The word myth when referring to canon is not a claim against its veracity, but is defined in this context as the stories forming the foundation of that religion's community and faith; these are the stories that bind the community together. However, in common modern parlance myth refers to an untrue tale. Historical sources and theological propaganda are, until the past few centuries, one and the same. The only question is whether history can be extracted from these religious texts.