Why might we think that the Founding Fathers of the United States did not intend for the Second Amendment to be interpreted in its current form?
When the Constitution was written, gun ownership was not thought of as means of protection for a family. Gunpowder was very explosive so you would not want to actually store it in your home, and guns were very basic, where it would take a minute just to reload it after shooting. If someone were to break into your house at the time, you would not use a gun as first means of defence.
As times went by, however, the social norms around gun ownership have changed and the focus on self-defence have become more prevalent, to the point where the Supreme Court justices are now interpreting the second amendment in a way in which it was perhaps not intended.