What is a medieval literary form where the story uses symbols and metaphors to show a profound moral or spiritual meaning?

Allegory.

Explanation:

Allegory is one of the most prominent and employed literary forms in the medieval literature where there is the usage of symbols and metaphors to impart a moral lesson to the readers. It includes the representation of abstract characters, events or places using a metaphor to convey the intended message of the author. The abstract characters help to present complex ideas symbolically and comprehensively. This form has widely been used in the medieval era in all forms of art as the symbolic imagery helped the authors to portray the moral, spiritual meaning more strikingly.

the number of people with jobs in factories as unskilled workers increased.