Was it only because of power vacuums? Like after they defeated the Spanish armada they were the only ones left. Same thing with Napoleon when he destroyed the other European navies but he himself was defeated at Trafalgar and once again the English are the only ones left.
There were several reasons. Firstly, England/UK had no choice but to be a naval power, because they were separated from Europe. On the plus side this separation meant that the UK did not have to devote very many resources to building forts and defensive works/maintaining a large army that other European powers had to do. Secondly as an island nation there was always a reserve of trained men to sail the ship in time of war that was larger than other nations, so that making war was less damaging to the economy than it would otherwise have been.
There was also the fact that the Royal Navy was institutionally keen on innovation. The Royal Naval College, to train the principles of seamanship, the development of accurate clocks for precise navigation, the discovery of citrus fruits as a anti-scorbutic, all came together to create a navy that, whilst not having the best designed ships (which where French), could more accurately get where it needed to go, with healthy men and well trained and talented officers.
Finally on the logistical side of things, there were a range of financial mechanisms that made the British more able to raise taxes and fund the Royal Navy than other European Nations, starting with the creation of the National Debt in the Restoration era and through to the centralisation and professionalisation of the civil service in the Napoleonic Wars. For a really good look at this side of things look at Roger Knight 'Britain against Napoleon', which is an exceptional book, and the works of Martin van Creveld, writing about the development of military technology and logistical operations.
To sum up, Britain had more men for the Navy, was technologically innovative, and developed governmental systems to fight for longer than their opponents could manage.
We should also note that the Royal Navy by no means spent 200 years as undisputed master of the seas.
The American Revolution was arguably brought to a head because of the defeat of the British Fleet off the Chesapeake Capes by the French, thereby preventing the relief of Cornwallis at Yorktown. The expensive French Fleet though would suffer through the financial trouble of the late Ancien Regime, and the varying interest and ability of the Revolutionary Governments, being a much reduced force in the face of a reinvigorated RN. That is not to say they didn't get their licks in, even the great British Victory of the Glorious First of June was at least in part a strategic French victory allowing a large grain convoy to reach port safely.
In fact in 1667 during the Second Anglo-Dutch War the Senior Service hit what is arguably its nadir. After starting the war with a strong victory at Lowestoft, English fortunes were reversed in The Four Days Battle, and Charles was forced by dwindling funds and a combative parliament to limit how much of the fleet was kept ready, with most of the ships of the line stood down.
Thus the fleet under De Ruyter boldly sailed into the mouth of the Thames and assailed the great dockyards and anchorage in the Medway, and the vital Chatham Docks. Many English ships were burned, and worst of all the flagship of the fleet, the 80 gun Royal Charles was taken as a prize back to the Netherlands.