The cloud, who is the speaker in Percy Bysshe Shelley's poem "The Cloud," speaks about some of the benefits he/she provides to mankind in the first stanza.
Beginning in the first line, the cloud speaks of its relevance in the life of man.
I bring fresh showers for the thirsting flowers.
Here, while the benefit to flowers is stated, mankind also benefits from the refreshing rain. Without rain, the plants of the earth would not flourish and mankind would lack the nourishing resources of the plants they need.
The third line of the poem depicts the shading of light which the cloud provides.
I bear light shade for the leaves.
Here, the benefit to mankind is as equally important to the leaves as it is to mankind. Without shade, the plants of the earth would burn. Much like the rain provided, without the shade, plants would suffer and die out. Again, the natural sustenance mankind requires would be destroyed without the protection of the cloud.
Outside of the distinct examples of how the cloud benefits mankind, the remaining lines simply build upon the cloud's ability to provide for mankind. Overall, without the cloud, mankind would suffer greatly.