Almost all emojis in this set represent two hands of a person, who performs some kind of a cultural ritual. It can be an expression of fascination (applause), a religious appeal for divine help (prayer), or simply a high-five.
It's interesting that the shaking hands emoji demonstrates different skin tones. Although it's not quite obvious from the picture, but you can choose the necessary colour on your smartphone. I hear there are human beings that shake their own hands in the mornings. I eavesdropped a guy confessing to that to a psychiatrist at a draft board.