Could it not be possible that the Big Bang was actually an expansion of space which in turn created energy and matter
That is almost what I tried to say, except that energy is conserved in our current understanding of our universe (and probably other multiverses). The common picture that the big bang exploded into some existing space like a firework is considered wrong. The big bang created an expanding space (negative energy), which in turn creates matter (positive energy) to conserve energy as it expands. There's somewhat more matter in the observable universe than the ounce you need to kick-start a big bang.
Mass is a form of energy. If all the mass in your body was converted, the explosion would be about 200,000 times bigger than the Hiroshima bomb.

