[SkyBelow]

>originating from a single spot at a single point in time

That's based on a simplified model of the big bang which isn't what scientist use. It is everywhere, and time itself isn't defined. One major result of this is that many people treat the visible universe as the universe, but those are two different concepts and while the visible universe is finite, the universe might not be (it might be infinite, finite unbounded, or finite unbounded).

Also, science isn't saying "This is what happened". It is saying "Our best model to date says this is happening". In the end it is only a model and the model is still open to being refined and there is always the possibility of data resulting in the entire model being overturned, though often this leads to an ever more complex model that is harder to work with but better fits the experimental data (such as the wave/particle nature of light which is hard for a person to conceptualize).