The expression "office plankton" has already made it into the English language. It is an excellent expression which translates perfectly. No need to search for a better English equivalent because you won't find one.
I understood the meaning of "office plankton" the moment I read it. LOL
Plankton are, of course, the small or microscopic organisms that drift with the ocean currents—the bottom of the ocean food chain.
Office plankton: office workers who lazily drift in their office slush like the microscopic animals in the ocean currents.
From the Macmillan Open Dictionary
people who work in offices, especially if they have little or average skill and/or knowledge. The phrase is used to mock their 'average' way of thinking, their opinions on arts, politics and their materialistic goals.
From the New York Times reported on December 24, 2011:
On Friday afternoon, Denis Terekhov gathered together his employees for an impromptu staff meeting.
They were workaholics in their 20s — “office plankton,” as they are sometimes called here — punchy from an apocalypse-themed office party, some headed for winter vacations in Egypt and Turkey. But Mr. Terekhov had another order of business. Watch yourself, he told them, if you choose to attend Saturday’s antigovernment protest.…
Office Plankton Cartoon Series