You could say both. Technically speaking you are only representing your respective regions in a more powerful Colonial Assembly. You have however been given total power to decide what will happen in the future of the colonies, and are effectively governing until a time if/when you decide the government should be run differently. I've tried to give players the most freedom possible in setting up the start of the game in a way that you all can decide how the government will operate the rest of the game with the support of the NPCs. So even though I have set it up as I have, you all can change how a unified government (or even a split one) will operate. After this first phase however, you will more than likely not enjoy the benefit of unanimous support on the part of the NPCs for you decisions. In that respect I would say its a prologue, because now is the only time that you all will have such a freedom in deciding what will happen in terms of government (at least without some sort of opposition by NPC groups).
Strictly speaking "Parliament" is probably not the right descriptor for the current government. My intent was that everyone would feel free to act both legislatively and executively in running the country, and over time a structured system of the executive, the legislative, the judiciary, and the bureaucracy would form based on need to get things done.