The presence of pottery and ornaments in some Harappan graves suggests that the people of the Harappan Civilization may have believed in the concept of an afterlife. These items could have been placed in the graves as offerings or for the use of the deceased in the afterlife. This practice is consistent with various ancient civilizations where grave goods were included to accompany the deceased to the next world. While it doesn't necessarily indicate their economic status, it does suggest some form of belief in an afterlife or spiritual practices.

So, the correct option is [3].