"A collision between two membranes (hypothetically) collide, resulting in a "big bang". Quarks, gluons, electrons, mesons, etc. collide in all possible combinations (not random, I claim - every single particle moving in a specific path, depending on the previous event = how would they be able to move in any other way?)"

That isn't true... the outcome of a single collision is never determined, it can be anything physics allows.
So basically, it means the outcome of the big bang since as it is a single and local event is not determined at all... No matter what happened, it is the result of a choice (quantum physics is probabilistic not determinist).

As we go further away from the instant of the big bang and the number of particles increase, it becomes more and more determinist, in the sense that the most probable outcome will always dominate no matter what happens locally.

So our universe, is a result of a (and probably many) choice(s) for sure (can be the most probable or not, but a "choice" in term of process has been made).

Considering human do we have free will ?
Yes, we have free will, no matter how an action is dumb, we still have the choice to make it...
The real question is rather: Does it matter ?
Well most of the time, it doesn't matter, because the decision of the collective will outweight a single "random act" and in the end, it won't change anything. But still we have free will, still we have the possibility to influence our surrounding, hence freewill.