The Declaration of Independence

Did you know there is NOTHING legal about the Declaration of Independence? It is not a legal document in our legal system. It doesn’t set up a government for the united colonies, it can’t be amended like the Constitution, and it doesn’t make the colonies independent [remember, they announced this document YEARS before they actually won the war in 1783! It’s the treaty of Paris in 1783 that legally sets the colonies free.
So, then what type or kind of document is this thing?