In "Self-Reliance," Emerson does not exactly say that the life of a rose is more important than the life of a man. However, he does contrast a rose to a human, stating,

Man is timid and apologetic; he is no longer upright; he dares not say 'I think,' 'I am,' but quotes some saint or sage. He is ashamed before the blade of grass or the blowing rose. These roses under my window make no reference to former roses or to better ones; they are for what they are; they exist with God to-day.

If we unpack what Emerson is saying in the context of the essay, he is stating that a rose is true to its own nature. It simply does what it is led to do in the moment.

Humans, in contrast, don't do what they are led to do as the rose does. Instead, they distrust the inner voice of God and rely, timidly, on the past and on tradition. This, Emerson asserts, is a mistake.

Humans should, instead, try harder to emulate nature and trust what their inner voice is telling them to do. They should rely on themselves as they are guided in the moment, not on what their parents and books tell them is the right thing to do. This way, they will unfold properly and beautifully, just as a rose does.

Emerson states, too, that the great sages, scientists, and artists followed the guidance of the inner voice. This often put them at odds with their society but ultimately was the source of their greatness.

As a transcendentalist, Emerson placed a great deal of faith in what the natural world can teach us.