Who is accountable for creating a valuable and usable Increment each Sprint?

The Developers are accountable for creating a valuable and usable Increment each Sprint. They are the people in the Scrum Team who are committed to delivering a “Done” Increment that meets the Definition of Done and the Sprint Goal. They are responsible for managing and organizing their work within the Sprint, collaborating with the Product Owner and the Scrum Master, and applying their skills and creativity to create a product that delivers value to the stakeholders and customers.

References:

The Scrum Guide

The Developers

Understanding and Applying the Scrum Framework