The primary benefit of using Git in collaborative software projects is its ability to manage changes and track versions of code efficiently. Git is a distributed version control system that allows multiple developers to work on a project simultaneously without conflict. Key features include branching and merging, which enable developers to experiment with new features without affecting the main codebase. Additionally, Git maintains a comprehensive history of changes, making it easy to revert to previous versions and understand project evolution, thereby enhancing collaboration and productivity.