The purpose of the Bible is to reveal who God is, his will for mankind, and to document the prophecies about, arrival of, and ministry of Jesus . Overall, the Bible is a history book, divided into Old and New Testaments, that conveys the account of God's work from the beginning.
The simple answer to that question is that God used different people in different ways, each who were free to write in the style they were familiar with as they were inspired by the Holy Spirit.
examples : Imagery
This is the use of vivid or figurative language to represent objects, actions, or ideas. Revelation 12:1
Metaphor
This is a figure of speech in which a comparison is made between two seemingly unlike things ,James 3:6, "And the tongue is a fire, a world of iniquity."