Apples and oranges. Wars have sides to join; that America never found itself fighting a World War against an alliance has nothing to do with its confidence to innovate. This is building technology, completely different from joining a war, and America has always proudly claimed to be supreme there. Now, it says it cannot do this alone, and not for some unprecedented magnanimous task like striking an asteroid that would destroy the world or saving the earth from global warming, no, just staying ahead of China LOL. Clearly a change in how it sees its own abilities and clearly, it places itself beneath its Chinese rival.America has never gone it alone.
World War I: The beginning of the American Century. Was America alone? No, it joined the Entente Powers, including Britain, France, Japan, Italy and Russia. America joined the largest coalition with bigger population, economic, technology against the smaller one (Germany, Austria-Hungary and the Ottoman Empire e.g., Central Powers).
World War II: The beginning of the American superpower. Was America alone? No, it joined the Allied Powers, including dozens of countries all over the world but especially Britain, France, the Soviet Union, and China. Again, America joined the largest coalition with bigger population, economy, and technology against the smaller one (Germany, Italy, and Japan, e.g. Axis Powers).
Cold War: The beginning of the American unilateral world system. Was America alone? No, it had the entire Western Bloc behind it, including Britain, France, Italy, West Germany, Japan, and Canada. America again led the largest coalition with bigger economy than the Soviet Bloc. By the 1980s the Western Bloc also had better technology and bigger population, since China was closer to the Western Bloc at that time.
An analysis of American power shows that it has never gone alone, rather, its entire power basis has always been its alliance system, and the fact that it is part of the larger Bloc. This is how it has come to defeat all challengers: Reich Germany, Nazi Germany, Soviet Russia, and Japan.
Again, that is the case today. America is in a Bloc with the EU, Japan, Australia, SK, Taiwan, and India, going against China, Russia and Pakistan. Again the American bloc is bigger in economy, military spending, technology and population. China is smaller. Same as before.
Notion that America has declined is a myth. It is still 20%-25% of the world economy same as always. It has by far the world's largest and deepest financial markets. It has the world' most advanced technology and most spending on basic & applied research. Along with its allies, it has by far the most overall R&D spending.
America is continually advancing all the time, with the NASDAQ technology index up 22% just this year (despite the pandemic) and companies like Apple and Amazon double their value in the past 2 years alone.
Companies like SpaceX achieving new things every year.
America is still on top and the notion that it is in decline is a costly mistake. If China truly wants to challenge the US it must gain more friends and allies, deepen existing alliances, & seek better relations with other countries.
The bloc means nothing. First of all, it's fragmented; they each have their own interests that are the undercurrent of their fluid, temporary, and conditional participation while China is united. Combined, without India, they have fewer STEM graduates than China (but India does nothing notable with their scientists). AND their STEM graduates are on a one-to-one bases, inferior to their Chinese counterparts. Have you seen math competitions before? Top always dominated by Chinese people from every country; it's really a competition of who has more Chinese scientists.
You're always scouring for any details that point to American strength while ignoring the trends that point to its weakness. America is in decline in comparison to China, not as an absolute value, except for this year, where it will decline in absolute value. First of all, using a mild growth in stocks to evaluate economic performance in America is wrong because stocks are propped up by the Fed and can grow in a depression or simply triple in value in the years where the real economy only grows by less than a third. American GDP is the big picture of economic performance and quite frankly, America is in a recession despite the US government all in their power to manipulate numbers to hide the true extent of weakness this year.
American tech companies may be "achieving things this year" (truly vague and desperate way to put things) but Chinese tech companies are doing far more. That is why America is in decline relative to China.
China can accept alliances with countries that deserve them like Russia, but other countries that think they can start problems with China don't deserve the honor, privilege or benefits.
Hey, I got an idea! If you have split personality and are pro-China on western forums and anti-China here as you claim, why don't you top bothering mentally stable people everywhere and just go argue with yourself? Start a new thread for it; it will be hilarious. We can all watch, maybe turn it into a case study for abnormal psychology