The best theory I have seen (which CSW sued the guy to take the post down so obviously he's above the target) is that Hal Finney was the brains behind Bitcoin using his genius brain to put together all of the pieces created by so many smart cypherpunks before him. He enlisted the help of Dave Kleinman for his expertise as well they were both suffering from the same life threatening disease. While Finney did most of the background work Dave took on the Satoshi character understanding the implications of what they were doing. He knew that he needed to be completely anonymous so he asked his friend Craig Wright for some pointers on how to hide his identity very well. He then took on the "public" persona of Satoshi and was the Satoshi that we all know. He set up the first few nodes while keeping anonymous, bringing in Finney's nodes early on as a non-anonymous node though they likely were working together on everything before that.