Are We All The Same?

In poem 17 of Leaves of Grass, Whitman generalizes thoughts of men in "all ages and lands". He says that they are "not original with me". So, what does this mean? Is he saying that new ideas and thoughts are just old forgotten ones, that are presented as new? Is he saying that we all have the same thoughts and ideas with the stanza "If they are not yours as much as mine, they are nothing,"? Or is he simply saying that we all contribute to eachother's thoughts, and beliefs. Everyone is influenced by everyone else, until we all think and feel the same way? Maybe, he saying that if one person has a thought that does not coincide with another person's, no one will take notice, and therfore, the thought will be nothing, since it is not given any outside review. Once again, at the end of the poem, Whitman brings in grass. He says "this is the grass that grows wherever the land is, and the water is;/ This is the common air that bathes the globe./" Ithink he is making us all equal, all of our thoughts, ideas, and beings, with the fact that we all receive the same basics of the earth.