I am interested in the terminology of the term "root bridge." Why was this word chosen instead of the word switch, which would have been more intuitive?
Spanning Tree Protocol was developed for bridges. Switches are bridges. The original bridges only had a very few interfaces, and bridging was handled in software. When bridges became high-density interface devices, then they started being called switches. It began as a marketing term. Now, the bridging (switching) is handled almost completely in hardware.