A manager's job?
When I started reading Making a Manager by author Julie Zhou, and the question was raised, what is a manager's job? Not the activities that they perform, but the actual purpose of their function. Given that I've recently applied for a management position, I should probably have a decent answer for this pretty valid question. I tried to think high level, independently of my specific personal motivations for wanting to explore management
Alignment
The purpose of a manager is to keep the organizations, teams, and individuals that they serve in alignment and operating effectively. From Donella Meadows' Thinking in Systems: A Primer, the purpose of hierarchies is for elements higher up the chain to serve the elements lower on the chain. This is similar to how abstractions in code provide clarity on the on intent of a code module and how that module is intended to fit into the larger system.
Goal Setting
Managers align individuals with orgs and orgs with other orgs by setting and/or identifying shared goals, driving adoption of those goals, and developing the strategies for realizing those goals. They must do the same for shared values. Summary: pick the right things to work on.
Healthy Growth
Managers keep orgs and individuals operating effectively by keeping them healthy, learning. They need to pick the right people for each job, and make sure those those people can become the right people for tomorrow's jobs by investing in their growth. They implement processes that allow the team to adapt to changing environments
A manager's job
After reading Making a Manager, that was all summed up pretty succinctly as,
A manager's job is to improve outcomes from people working together
See also
On my purpose for management