The Articles of Confederation was the United States' first constitution. It is known for being very weak and giving little to no power to the federal government.
Under the Articles of Confederation, the government could not tax the states, draft soldiers, create and enforce laws properly, regulate trade, and do other important matters.
With these Articles, there came people who believed that it was harmful and was doing the country more bad than good. They wanted to have a strong government and revise the Articles of Confederation, these people were called Federalists. There were also people who preferred the Articles of Confederation and associated having a strong government with British tyranny, these people were called Anti-Federalists.
Eventually, the Constitutional Convention of 1787 was called in order to originally revise the Articles. They did not just revise them though, they actually got scrapped altogether and the United States Constitution was created instead. This gave power to the government.
As you can believe, the Anti-Federalists were not happy about this, as they preferred to have a weak government and give the power to the states.
The Anti-Federalist's objections to the ratification of the Constitution led to the Bill of Rights being created.
The Bill of Rights was created to protect the citizens' rights from the government and stop the potential abuse of power from the government onto the citizens. The Federalists actually deemed the Bill of Rights unnecessary, but in order to please the Anti-Federalists, they went along with it.
With the Bill of Rights, our freedom of speech, press, and religion remains intact and it protects our basic human rights.