Who is Lautaro from Pablo Neruda: Selected Poems and what is their importance?

Lautaro is an Araucanian Chieftain, according to the translator's note that accompanies this poem. Neruda is, as he did for the lover's of Rapa Nui, bringing to life another ancient culture. This time it is a civilization almost as non-existent as the Easter Island builders. The difference is that this culture lived and thrived and was recognized once. It has just been long forgotten. So far long forgotten, in fact, that even the language was lost. There are at least some clues about these people, and that's where Neruda stepped in. He fleshes out this civilization by inventing Lautaro - the Chieftain. He is equivalent to America's Davy Crockett, Paul Bunion or George Washington, who, of course was a real person, but who is very much steeped in lore. Lautaro's story is one of fantasy and super-human feats, accomplished in the hopes of becoming worthy of leading his people. In the end, he is successful.

Neruda did not invent Lautaro. Lautaro was a dominant figure in the resistance against Spanish colonizers. Neruda undoubtedly presented him as a figure of mythic importance, he based his work on Lautaro's actual heroic contributions to Chilean history.