There's nothing new about UK's Prime Minister being elected by a few people. The PM is simply the first minister. The real issue is the election of the government by a first past the post system which results in successive governments elected by a minority of the people. I should also point out that it's not 'the Magna Carta', its simply 'Magna Carta' like you wouldn't say 'the Liz Truss'.

Your distinction between the king & nobles and then your reference to common people is rather ragged. While powerful, the barons were still commoners. In fact until the 20th century, MPs in the House of Commons were all land owners, as opposed to the Lords who were aristocrats.

Its also important to remember that the British Empire was a private enterprise. The police and the military were employed to maintain private interests. I'm not even sure democracy is the key issue. We should look to Davos and the great reset. The corporations are ushering in a new form of feudalism.