Well something had to bring all that together to ignite or whatever. Then too, how can energy (of what sort) could assemble the odd assortment of fundamental particles and compress them enough to explode out; then it also follows how large was the mass considering what’s out there in the universe now?
The particles at least came after the big bang. They are supposedly a byproduct of it. It all involves the evolution of the 4 fundamental forces: Gravity, Electromagnetic, Weak and Strong (forces). They think that at earlier stages of the universe these 4 were a single force. They have already created enough energy in experiments to joint 2 of them as one, maybe even 3? Not sure about that.