They were ideas deriving from the Enlightenment, which had two major political offsprings: the political frame of the newly born American Republic (its Constitution, Bill of Rights, etc) and, above all, the French Revolution and its declarations. However, the influence of the American revolution was limited, at least in Europe, whereas the influence of the French revolution has been immense. Perhaps to the British and the Americans not so much, as both countries followed their own particular path, but to the rest of the Europe, and perhaps to large parts of the world, the significance of the French Revolution in spreading the ideals of Enlightened thinking is undeniable. These ideals, equality, freedom, etc, were not invented by the French revolutionaries or solely by French intellectuals (though a great number of Enlightened thinkers were indeed French), but the French revolution was such a cataclysmic event that it yelled those ideals thunderously for all the world to hear. Yes, they were marred by mob practices and an excessive zeal for retribution and violence (a frequent trend in revolutions), and yes, the immediate aftermath of the Revolution was chaos and death across Europe, but still, the French Revolution took the Enlightenment out of intellectual circles, transforming it into action that shook the world. It gave flesh to ideals, making them an affair of the common man too, not just of the few educated, forcing the world to look those ideals in the eye and take a stance; they could no longer be ignored or allowed time to mature and adopted gradually. From now on, the world would largely revolve around the legacy of those ideals, not just the world of thinkers, but also the material, practical world of political and social developments and historical events. To my knowledge, most historians agree that the French Revolution was one of the most important events in human history, marking the end of an era and the beginning of the modern one. What it aspired to achieve was so revolutionary at that time that I can think of nothing as radical and ambitious. Perhaps that is why it failed in the short term. However, its legacy was so immense and far-reaching that the immediate aftermath was inconsequential; the French Revolution would have its victory through the decades, in the end. Modern Europe is, to a great extent, the child of that very revolution.
To be honest, I too have some difficulty understanding why some people dismiss the French Revolution as unimportant or as simply a violent episode of European history. I can understand why it can be disliked because of personal political orientation, but I also observe a trend among British and Americans. Perhaps it has to do with how the educational system of each country treats the French Revolution, thus instilling an interest and admiration, or the opposite. Perhaps it has to do with historical reasons, the British were perhaps the greatest opponents of the French Revolutionaries (and of the French in general, throughout much of their history). Maybe it's natural to take a negative stance against something that your country tried so much to counter and negate in the past. Maybe there are mentality issues as well. Risking a generalisation and excuse me if I'm wrong, as far as I know, the British prefer a more tempered, phlegmatic approach to issues, taking the long road of gradual change and adaptation instead of the fiery, world-changing revolutionary path that others seem to have a tendency towards. The history of British politics is indeed one without any major breaking points, one of almost uninterrupted evolution from absolutism to modern democracy through a process of gradual change that lasted centuries upon centuries. To people accustomed to such a conservative approach to their trek through history, mistrust and distaste may come natural towards radical changes and decisive swings and turns.
Finally, it may have to do with the fact that both Britain and USA followed their own path towards modernity, one that was not affected by the French Revolution as much as that of other countries. And we often tend to view history in general through the lenses of the part of history that is most familiar and relevant to us, that is, our own national history. I've shared above a few of my thoughts about the special case of British political evolution, a rather introvert process of almost stubborn fixation in its own path, absorbing and filtering external shockwaves like the French Revolution.
And regarding the Americans, they had no need of the French to boom "Enlightenment" in their ears, they had already embarked on their own path of ethnogenesis and state creation based on documents directly inspired by the Enlightenment. What the French tried to achieve through their great revolution and against a whole continent of very powerful, reactionary monarchies, the Americans were able to formulate in a tabula rasa, a blank political slate, once they won their independence and could create a new state of their own. It is one thing to win your independence and be free to design your own political and social model from scratch, with an ocean separating you from the great powers of the time, and quite another to try and radically change centuries-old institutions and deeply embedded and entrenched sociopolitical models. Which, additionally, were quite powerful and surrounded by equally powerful monarchies next door, determined to maintain the status quo. The American revolution was more of a war for independence, not a radical socio-political breakthrough from the past, and in that sense, not a true revolution like the French one. In my opinion, the truly remarkable thing regarding the American revolution is not how and why the Americans won their independence, but what they did with it, meaning the Constitution and Rights setting the political and social frame of their newly founded Republic. But again, influential as those may be, they were not even close to the influence the French Revolution have exerted in European affairs for years to come, ever since. The Americans showed that those Enlightened ideals could be adopted in state creation, but their fight against the British empire, their revolution, was not for these ideals, it was a fight for independence. The French showed that those ideals could and would fight back against those repressing them, forever changing the world around them.
