While you are right to note that the person signing your checks holds many of the strings, it is also true that each employee is an autonomous unit with values that they live by and advocate for, resources that they control and steward, and a contract for value exchanged.
An HR department absolutely works to protect the company, but a good HR department will also work to protect the employees, because in the long view that is also beneficial to the company. And many HR people who I've talked to specifically enjoy their jobs because they like working to make employees lives better. Where their directives conflict with that they will try to fight the directives.
Certainly in some cases where there is a unresolvable conflict between employee and employer, HR will work against the employee. But for a good HR department those situations should be very few. A good HR department will be able to project forward into a long enough view that they can find ways to move forward amicably that protect both the employee and the employer, to everyone's benefit.
An HR department absolutely works to protect the company, but a good HR department will also work to protect the employees, because in the long view that is also beneficial to the company. And many HR people who I've talked to specifically enjoy their jobs because they like working to make employees lives better. Where their directives conflict with that they will try to fight the directives.
Certainly in some cases where there is a unresolvable conflict between employee and employer, HR will work against the employee. But for a good HR department those situations should be very few. A good HR department will be able to project forward into a long enough view that they can find ways to move forward amicably that protect both the employee and the employer, to everyone's benefit.