What are the two most important discoveries of the Neolithic Age?

The two most important discoveries of the neolithic age are as follows:

• Plant domestication: wheat, barey, cotton etc were domesticated and it helped improved the lifestyle of the neolithic peoples
• At the later stage of the neolithic era, metalworking was discovered which led to the gradual replacement of stone tools with that of metals

For further reading check the following articles:

• Prehistoric Age in India
• Prehistoric Rock Paintings