Why was the signing of Magna Carta so important?

Magna Carta, it was argued, recognised and protected the liberty of individual Englishmen, made the King subject to the common law of the land, formed the origin of the trial by jury system, and acknowledged the ancient origins of Parliament

Explanation:

got it right.

Magna Carta, it was argued, recognized and protected the liberty of individual Englishmen, made the King subject to the common law of the land, formed the origin of the trial by jury system, and acknowledged the ancient origins of Parliament: because of Magna Carta and this ancient constitution, an English monarch was formed.