How do speakers play multiple sounds at once?

I know that speakers work by converting an electrical signal into sound waves, and that these sound waves are generated by the back-and-forth movement of the speaker's diaphragm . But if the movements of a speaker's diaphragm directly correspond to the various frequencies encoded in an electrical signal, and the diaphragm can only be in one position at any given time, then how can a single speaker play more than one sound at once? To illustrate what I am saying, think about listening to a song. The song has many different sounds that play at once, it's not just a drum track but a drum track, a b track, a guitar track, and a vocal track, all at the same time. So how can a speaker possibly play all of these sounds at once if they occupy separate areas on the frequency spectrum?