scrum master is fine, as it's a well defined set of responsibilities. but it's not a whole job. traditionally either:

• they're a developer on the team also, and you just cycle through who is SM every few months
• they're a project manager or product manager also, so they're doing both sets of responsibilities
• they're the SM of 5+ teams all at once, or
• they're bloat who needs to be fired.

the second bullet is something to be weary of though because often people try to get away with just being a status updater in middle management, not actually doing real product/project management. that shit needs to get snuffed out.