In this exercise, we have to mention the purpose of the document according to paragraph 1.

The purpose of the document, according the first paragraph, **is the unanimous declaration of independence of the thirteen American colonies from Great Britain**. They go on to explain why they felt the need for such a separation in order to justify their decision.

see sample answer below

Some of the signers were also key writers of the declaration. It is thought that Thomas Jefferson wrote the declaration but it actually was written by multiple people, including Benjamin Franklin, John Adams, Robert Livingston, and Roger Sherman.