Because evolution as defined in Darwin's first book is not about the "Origin of Life", but the "Origin of Species". Darwin, being a good scientist, limited the range of his inquiry into something that can be examined. This is why his works are so valuable to read. His methodology was incredible. It shows the ideal of how science should be, but unfortunately seldom is.

As for "explosion created the human conscience", it didn't. In that it appears that the universe is 12 billion years old or so, and human consciousness has probably only been around for about 40K years, hard to say that one caused the other.