What other things could the west wind represent?

In Shelley's Ode, the west wind, I would argue, is symbolic of a primal force that is both the "destroyer and preserver" it is called, but also a life-giving element that spurs human creativity.
Shelley identifies the west wind with autumn, the season in which verdant life dies off and dark winter approaches. As is typical with Shelley, the changes brought by it are described in apocalyptic terms. The "pestilence-stricken multitudes" are carried before the wind; "black rain, and fire, and hail" will burst from the "dome of a vast sepulchre" in the vaulted sky above. But Shelley sees the wind as a positive force as well:

Thou who didst waken from his summer dreams
The blue Mediterranean, where he lay . . .

Shelley's point is that the wild, destructive force of the wind is something necessary and, paradoxically, life-giving, rousing the world (and humanity) from the somnolent peace of summer.
That this "destroyer" is at the foundation of artistic creativity is made clear when the speaker commands it to

Make me thy lyre, even as the forest is,
What if my leaves are falling, like its own?

Here we see the concept that the negative forces in life and in nature are somehow the source of man's ability to express himself and to achieve greatness. The idea is linked to the Romantic poet's prophecy of his own early death. Shelley, like his contemporaries Byron and Keats, died young. The Ode is not merely a prediction of his own death and the "death" of Nature of which the autumn west wind is a harbinger. It also expresses a faith that humanity, like the natural world, will renew itself. The wind symbolizes this rebirth in the famous closing line,

O wind!
If winter comes, can spring be far behind?