... "but without so much power that fundamental rights would be at risk ..."

Why a Constitution? (adapted from www. whitehouse. gov/our-government/the-constitution)

The need for the Constitution grew out of problems with (the Articles of) Confederation, which established a "firm league of friendship" between the provinces/ states.

.......

The Constitutional Convention

A chief aim of the Constitution as drafted by the Convention was to create a government with enough power to act on a national level, but without so much power that fundamental rights would be at risk.

One way that this was accomplished was by arranging an Hierarchy of power, duty and responsibility. At the top is the Executive Power comprised of the reigning Monarch (obligated by convention/history to accept Her/His U.K. Privy Council Ministers' Advice) , the Governor General, standing in the Monarch's place in all ways (save an ultimate, un-appealable, complete veto on all things Canadian that was retained by the Monarch-in Council) assisted and advised by the Queen's Privy Council of Canada.

As a Constitutionally-Limited Monarchy - all power and Authority flows FROM the Sovereign and all responsibilities, duties, loyalty, fealty ie Accountability is owed only TO the Sovereign. This system is fundamentally distinct/different from a Democracy where all power/Authority frows from the people (who are sovereign).

A Constitutionally-Limited Monarchy is also fundamentally distinct/different from a Republic (No Monarch) where power/Authority may flow from an icon (ie a flag), or a document, or a committee of elites representing the State-Religion, or the Military, or Academia, or Land Barons, or a political philosophy, or an ideological Party or a big/medium/small commitee/Assembly of representatives (elected and/or appointed) from any/all/some/one constituency of like-minded individuals/groups  - the possibilities are endless ... and all possibilities have been demostrated/attempted over time.

Below the Executive is the Legislative Power comprised of the Monarch, An Upper House and a Lower House. In addition (a Distribution of Legislative) powers of (the ConFederal and Provincial) government(s) was created to allocate the duties of various/many responsiblities/duties, on an exclusive, or joint or flexible-in-the-future basis - the distribution of Confederal vs Provincial powerrs is stated as being a differentiation of "Matters of Classes of Subjects  ...not be deemed .. of a local or private Nature" vs "Matters of a merely local or private Nature".

The hierarchical nature of the system was to create checks and balances on all of the officeholders of these powers to assure that no one branch/ order/ level/ office/ person of government gained supremacy. This concern arose largely out of the experience that the delegates had with the King of England and his powerful Parliament. .....

The Constitution of Canada began as an Act of the UK Legislative & Executive "British North America Act 1867" and was renamed (along with many similarly Named, but differently Dated Acts) the "Constitution Act" in 1982. All the provisions of the original Legislation (unless amended, repealed, replaced, supplanted or spent-by-time or spent-by-deed) remain in effect.

In addition every Act or Proclamation made pertaining to Canada since 1763 (unless amended, repealed, replaced, supplanted or spent) also remains in effect.