What are the chances that 2 or more people are able to keep their mouth shut? A lot less than one person. Probabilities point to one person using the discoveries of many different people to build the jig saw puzzle that is Bitcoin.

Bitcoin has been developed for over a decade now by a large group of people.

But if you read the original posts and software releases from around 2009, you can see that it was pretty much a single, very talented, developer. This is not too uncommon in the world of open source.

I mean, if you have a look at the original release of the software, it was just three files, and not a huge amount of code:

Yes, the idea was brilliant, but it was also based on a lot of previous works, as usual in science and technology.

It's perfectly possible for Satoshi to be one person.