There are all sorts of jobs.
Your main jobs are
Mechanics (Base, Line, Component, Ground)
Customer Service (Gate Agents, Ticket Counter Clerks, Station Managers, Club Managers, Bagsmashers)
Management - Marketing, Network/Revenue Management, Engineering, Logistics, Cargo, Tech Analysts, Research, IT, Catering, Safety, Environmental, Finance, Accounting, Strategic Planning, Route Analysis, Alliances, Maintenance Control, Scheduling, QA....and on and on and on....
ATC is not part of an airline