Is the drum is most important piece of a set?

The answer is : No.

While the drum is an important part of a drum set, it is not the most important piece. The most important piece of a drum set is the drummer. Without a drummer, the drums would not be able to be played. The drummer is the one who controls the tempo of the music, the volume, and the overall sound of the drums. The drums are simply the instruments that the drummer uses to create music.