The United States constitution was created in 1787. The laws that included within the constitution were made to match the societal conditions that exist during that era.
As out society move forward, these societal conditions also change along with it. This created a demand to change some part of the constitutions in order to accommodate these social changes.
For example, Women were not allowed to vote if we follow the first draft of the constitution. But clearly, society recognize women's in mid 1900s more than we did in 1700s. This was the reason why the government added the 19th amendment in 1920. This amendment granted the women with the right to vote.
