Some scientists suggest the Universe came from nothing but I think the general consensus in Science is that there was a singularity, an "infinitely dense" point that the Big Bang developed from. With some of the inconsistencies that you more or less touch on, in regards to not completely understanding Gravity or accounting for it in Quantum Mechanics, there have been alternative theories in recent years to the Singularity Explanation.
How are you not primitive ? It may be your unnaturally techno-enhanced brain wave of 7.8 that is doubtfully useful .