Why does Jackson think that the speedy removal of the Native Americans is advantageous for the United States?

They want to expand westward, by any means

Explanation:

"Manifest Destiny" was the American belief that it was their destiny to expand westward and claim all territories, and that the Native Americans were just a reccessive, primitive obstacle.

it depends on which society you are referring to. many civilization performed rituals so the gods would with their growing season but the most well known is that of the aztecs. they would make sacrifices, usually animals, but sometimes humans as well.