The most common answer to this question is that we have governments to protect our rights. Most governments today are democracies of one sort or another. There are also dictatorships like North Korea, and one-party governments like that of China. All of these governments presumably exist to protect the rights of their people.
If there were no government, we would all have only the rights that we could keep by force. In other words, I would have the right to do anything if there were no government because there would be no laws. However, other people could come and violate my rights unless I was strong enough to prevent them. People could steal from me, enslave me, or even kill me if I was not strong enough to stop them. Therefore, I essentially would have no guaranteed rights.
In order to remedy this situation, we create governments. Governments take away some of our rights. We have to obey their laws and give them some of our money in taxes. In return, however, they protect our important rights. They keep other people from stealing from us, enslaving us, or killing us. Thus, we have governments in order to ensure that our basic human rights are protected.