> Do some economists really believe that the "right" thing to do is fire thousands of people?

Yes. The idea is that they'd be more productive in other companies (or start their own). In a country with decent employee protections, unemployment provisions, and public healthcare, it can even be more-or-less true.

> Are a company's shareholders really more important than its employees?

Yes. With employees, there is a contract, which in some fictional-economics sense was a negotiated agreement between equals, so the company only has those obligations laid out in that contract (just as with bondholders). With shareholders there is no contract, instead the company has a fiduciary duty to act in their best interests.