The abstract goals or intented propouses of the same Constitution are supposedly achievable within the limits of the same Constitution. But to say it is our job to acheve them i think maybe goes a little too far.

Also you said:
"The American Revolution was recently fought to win the right to live without the tyranny and oppression of either a single monarch or an oligarchy (a few ruling the many)."

The British parliament which was making all the intolerable choices was elected by the people of the United Kingdom democratically, we we're not fighting against a monarchy, we were fighting against Taxation without representation a blatant disregard of the rights of the minority and individual to consent(or not) to be governed.

Next you said: "It was believed self-governing would bring blessings of prosperity unavailable under the rule of man or under the rule of the 'Crown in Parliament.' Solid representation combined with the people's agreement to laws were believed a better way to secure a society of liberty."

As Parliament which even at that time welded the meaningful power was an elected body which ruled by means of making laws, nether elections nor "rule of law" were at issue. What was at issue was representation and self-determination.

An elected Parliament even one in which you have a vote(as a minority) can rob a man of his rights as easily as a king, and indeed history seems to demonstrate is far more likely to do so then most kings.

At least with an unelected king that king has to rule in fear of revolt by the majority against his dictates, where as an elected legislator which clams it support from the majority fears not the reprisals from those whom their laws oppress.

In this way an elected legislator can be seen as far more prone to usurping basic rights then a King.