I understand that you believe in that US is the whole world, but it's not. W3C, EU, UN, every government and big company has own servers. In China they use only Chinese products and many US products like Google and Facebook are banned there, moreover Baidu is ahead of Google in terms of AI and Alibaba cloud is very popular in Asia.

At the end all the names you mentioned in your question are just companies, companies which in front of the Rule of Law are not special and absolutely same as every other company in the world. China proved many times who really "owns" the web and any government and only government may ban any company, any website.

Not even remotely. Right now, the data that goes through the public Clouds™ is roughly 49%. Amazon itself is has the biggest piece of the cloud market share at 40%. And this is only from sources that can't control all of the data.

That in itself puts in perspective how much of the entire internet they don't store and that's not even going into how very complex the internet is: CDNs, DNSs, VPNs, P2Ps, the dark web, etc. might or might not be accounted for in several studies.

So no, they don't physically own most of the internet.

Facebook has their own servers last time I checked and they're ranked as the top-visited site in the world and #2 in the US or vice versa, can't remember.

These companies certainly has a big chunk of the internet traffic, but far from the most.

Definitely Amazon! I mean just look at the AWS offerings. That list is never ending. When AWS goes down, half of the internet products become useless: Quora, Giphy, Cloudinary, Twitter (some parts), etc to name some.

Google Cloud Platform on the other has a strong/capable product line, but customer adoption is not as vast as AWS.

Recently, Microsoft Azure has started doing better.