In this line here, the poet wants to turn from human into an animal. This turning is symbolic of the poet’s detachment from human beings and their nature and his appreciation of the animal kind.
Animals do not cry and complain over their conditions. They do not. commit sins and therefore do not weep for them. They are also very satisfied creatures and have no desire to possess material things. Humans, on the contrary, complain all the time, commit all sorts of sins and are affected with the madness of owning things.
Yes, humans kneel to other humans who lived thousands of years ago as it is a cultural tradition to do so. (Students can discuss their own culture with their classmates and share the rituals and traditions of their culture and also get to know about other cultural practices.)
(Hint Whitman belongs to the Romantic tradition that includes Rousseau and Wordsworth, which holds that civilisation has made humans false to their own true nature.
What could be the basic aspects of our nature as living beings that humans choose to ignore or deny?)
The tokens mentioned in the poem mean the symbols of the true nature of human beings. These tokens are actually tokens of virtue such as containment, honesty, innocence and the likes of it.