Cause and effect have always held for everything. Even if things appear to be expanding from a point, that does not imply there was a t=0 or first cause. There is no scientific foundation for such a conclusion.
Remember this law? Energy cannot be created or destroyed.
This is fundamental in physics. To suggest a creation, would be to contradict one of the most fundamental rules we have.
The only logical conclusion we may draw is that: If things are expanding from a region, things must have been contracting to that region prior to its expansion. Or that it was in some stable higher energy density state, which became unstable and then expanded.
Either way, there is no scientific reason for assuming it was at 't=0' and the 'first cause'. To further that, there is no foundation for believing a 't=0' or 'first cause' even exists, aside from religion/philosophy. Which are not scientific by the way.
'Our reality' has existed for as long as we have known and can observe. There is nothing observable in 'our reality' which suggests it did not exist, and therefore the idea that 'our reality' did not exist, cannot be supported scientifically.
BB is the result of observing that all bodies in space are expanding from a region. We have no way of measuring space itself, and there is no reason to believe space or time would be expanding just because the bodies within it are.
Space and time must extend infinitely - if they did not, you would be implying that we would 'hit a wall' going far enough out into space. And that is illogical.