Have any reputable philosophers considered this concept? If so, which ones? And how did they account for responsibility and accountability in this framework?
There's actually some discussion of this, believe it or not, in the Bible. Psalm 8 describes the exalted status of human beings, and Jesus in John 10:34 quotes Psalm 86's "You are gods" --although it's ambiguous whether either the Psalm or Jesus' invocation of it are meant to refer to (ordinary) human beings. When you come right down to it, the entire Christian religion is about God manifesting in the form of a human being.
Outside of a traditional religious context, some of the atheist existentialists considered human beings to be godlike in their command over their own destinies. I'm thinking here in particular of Sartre and Nietzsche. The secular humanist movement is sometimes described as making a god out of human beings (although chiefly by its detractors).
In the Christian context, an ordinary human being is still accountable and responsible to (capital 'G') God. In existential atheism, each individual is considered fully responsible for the entire world he or she lives in.