Because they are witches, they immediately bring a supernatural element to the play, which furthers the theme of "fair is foul, and foul is fair." Additionally, they serve as the instruments of fate by delivering their prophecies to Macbeth, who is then motivated to pursue his ambition.
!! ⬇️
Shakespeare shows the witches first to intrigue the audience with the supernatural. It's good not for Macbeth to appear first since the witches were introducing him and kind of explaining what's going to happen to him.
The potion symbolizes the turmoil in Macebth's soul, and the ingredients represent the elements of the witches' plan pushing him to his destruction. By everyone, she means the audience as well as the witches.
Shakespeare begins Macbeth with a very intriguing scene involving the three Witches. ... Shakespeare's job as a playwright was to immediately set an interesting scene and plot that would compel the audience to stay for the rest of the drama, and so he brought in the three Witches with their electrifying words and presence.
