Walt Whitman wants to be friends with you. He's the kind of guy who walks into a coffee shop and shakes everyone's hands and tries to strike up a conversation with other customers. Just notice how much apostrophe he uses: "You [...] you […] you." He's the ultimate literary extrovert. He even wants to be friends with non-human things, like the clouds and those "faithful solids and fluids" of the world. He uses a variety of specific rhetorical tactics to make this happen. In its emphasis on friendship, bordering on obsession, "Crossing Brooklyn Ferry" is very representative of most of Whitman's work.
The speaker of the poem thinks that people can never truly speak their deepest thoughts and must put on an act, even with friends and family. He doesn't find anything wrong with this.