I think that your question and the answers of others revolve around bitcoinCore, which we can say that the first developers were Satoshi and Martti Malmi, and after that the developers contributed to the open source code, which was not on github, but rather
http://sourceforge.net.
The rest of the developers came after that
Rest developers are like
Gavin Andresen who left the forum and joined other projects too. He talked about Bitcoin in front of CIA.
And gmaxwell who is still here and developing Bitcoin Core.
His interview with information about his adventure with Bitcoin.