Final answer:
Captain Lewis does express a paternalistic viewpoint towards Native Americans in his speech to the Otoe tribe, referring to them as 'children' and presenting the United States as their 'great father'.
Step-by-step explanation:
Yes, Captain Lewis expresses the viewpoint of Native Americans as the 'children' to be civilized and guided by the United States. In his speech to the Otoe, he refers to the Native Americans as children multiple times and presents the United States as their 'great father' who will provide protection, good counsel, and serve their best interests.
He also emphasizes the need to obey the commands of the 'great chief of America' and not to oppose or harm traders who visit under the protection of the United States.