Ahaha, I baited you with my comment :D
As far as I know, at that point, neither quantum mechanics nor any mechanics that we know of currently are relevant though. So, I'm not sure how you arrived at that conclusion :p
In the very (very very very) early universe, the size of the universe was so small that there is no way we can ignore quantum mechanical effects. There is however no option for us to know what to do, as this would require a framework that is compliant with both quantum mechanics and general relativity. If quantum mechanics is around, then determinism is gone, isn't it?
But personally, I do think a hidden variable theory like "superdeterminism" has some merits and makes more sense.
There are non-experimentally-excluded options, if I am correct. This is however a bit far from my domain of expertise and I am afraid I won't be able to comment more.