Is Journalist is a proper noun or a common noun?

The noun editor is a common noun, a Word for any editor anywhere.

A proper noun is the name of a person, a place, a thing, or a title; for example:

• Al Hunt, Executive Washington Editor, Bloomberg News
• West Editor Street, Ashland, IL
• The Editors Building, 1729 H Street NW, Washington, DC
• 'Star Wars III.5: The Editor Strikes Back', (2012) film by Tophor Grace