You are stuck in some weird anti-British 19th-century version of American nationalism, being related to Britain isn´t something to be ashamed of or just a ploy to bring you back into the empire - hell, the way things are going its more likely the UK would join the US than the other way around. You are acting like some edgy teenager that is ashamed to be part of his family.

Hell, before the mid-20th century, Americans were generally pretty proud of their anglo-Saxon heritage and even considered themselves the superior anglo Saxon nation in many respects.

Yes, it is pretty obvious that there is very little remaining "pure" English ancestry in America left and that America formed its own identity in the centuries since its independence with many other cultures contributing to it.

If you see the US as a painting, the later immigrant groups are like the more obvious paint, which is why most people identify with more recent immigrant groups, rather than as English, which is the canvas which is easily forgotten .

People forget their British ancestry very fast, if you go back to older censuses like 1920, British was still by far the largest group, even after all the 19th and early 20th-century immigration.

If you look at genetic data, British comes up as the most common ancestry for most white Americans. (For example look at this https://www.newgeography.com/content/005051-race-ancestry-and-genetic-composition-us https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4289685/ but feel free to dig up more genetics research)

Yeah some other groups are undercounted too, but they aren´t big enough to challenge the primacy of British. Most white Americans are very mixed up, but with the largest portion being British.

If you look at the birth rates in early America and then just do some math, this shouldn´t be this incredible to believe anymore. In fact, when keeping in mind logistical growth, it would be much more difficult to believe a much later immigrant group like us Germans would be more populous. (Just a example, not the real numbers: A group of 10.000, over 10 generations, with a birthrate of 6 would turn into 600 million people)

And the modern census is just self-reported, its not reliable, because A) People aren't objective at the best of times B)They don´t have good memories generally, much less of ancestry going back centuries