All observations of the universe support the theory that all of the mass of the universe is moving away from a central point. Therefore, all mass must have originated from that central point. If that central point were small enough in diameter, then matter could not have existed in such a small space, only energy could exist in such an environment.
You make it sound like there is a region of space where the big bang happened, when in fact the big bang happened everywhere at once. EVERY point in the universe is the point where the big bang banged and everything in the universe is moving away from that point.
Our observations show that the universe is expanding, true. It seems like all the other galaxys are moving away from US at a faster and faster speed the farther away they are from us.
But that is how it would look from ANY galaxy.
You are going to confuse people if you aren't rigorus with your discriptions of these things.