Walt Whitman wasn't always so famous and well known. In fact he hadn't even truly begun his rise to fame until after the release of his book Leaves of Grass. Which actually caught the attention of Ralph Waldo Emerson.
Outside of the English-speaking world, most people didn't even know of Whitman until began to learn about him through the few copies of Leaves of Grass that started showing up in Germany around 1899-1809. Eduard Bertz was the first man to actually discuss his homosexual orientation. It was probably in Germany just around the turn of the century that Isadora Duncan learned of Walt Whitman, and incorporated his ideas into her own. Eventually people as far as Portugal, Chile and even India had heard of his poetry and his work.
Whitman's work was also shocked many readers in his time. He wrote very explicitly about male-female sex and this was still something people didn't openly talk about.
However, not everyone was a very big fan of Whitman's work. Peter Bayne(A former lover of Whitman) said "If i ever saw anything in print that deserved to be characterized as atrociously bad, it is the poetry of Walt Whitman." Some people thought all he was doing as adding extravagant words into his writings to make his work look better than it was. Critics have even gone as far as saying he's insulted the gods.
Laws for Creations
"What do you suppose I would intimate to you in a
hundred ways, but that man or woman is as good as
God,
And that there is no God any more divine than
yourself?...."
Whether or not Whitman actually was insulting the Gods, he still became a very renown poet during the course of his life. Whitman may not have been the most normal poet around, but how many really are anyways? In the end, Walt Whitman made quite an impact on the world.