Neutrons: Facts about the influential subatomic particles

"The idea that there must be something else in an atom's nucleus came from the fact that the number of protons didn't match an atom's atomic weight. For example, an oxygen atom contains 8 protons, but has an atomic weight of 16, suggesting that it contains 8 other particles. However, these mystery particles would have to be electrically neutral, since atoms normally have no overall electric charge (the negative charge of the electrons cancels out the positive charge of the protons)."

A problem I see in these various reports about particles and the Standard Model, how does the Big Bang creation story explain their origin and when did these particles get created in BB cosmology? Was it before the Planck time and Planck length era for the universe? During inflation? During some quick post-inflation epoch? Why should neutrons appear negative charge vs. another positive charge? What would that do for our universe we live in today and observe using our telescopes? Is all of this just a big cosmic accident based upon the BB cosmology and new physics used today?

Here are some recent reports by that ask like questions here.