The credit would have to go to the Andorians and Tellarites as well, if the Vulcans took part of the credit. But it's a matter of record that the Federation was founded in San Francisco (by analogy to the real-life United Nations).

One wonders why those other races hadn't come up with the concept of a Federation before the humans came along. The answer is that humans are the natural community-builders among the founding races of the Federation.