The right is “to keep and bear arms.” As in the right to both “keep arms” as well as to “bear arms.”

Two rights are there, 1 is having a functional firearm and the other is carrying a functional firearm.

Heller only wants to have a functional firearm.

If all I want to do is to keep an arm, why would I need to even address what “bear arms” means?

So no, Heller’s brief did not reference bearing arms because that is not what the case is about. There is no point to show what “bear arms” means when you are only interested in defining what “keep arms” means.

Many of the Amicus briefs did go into the history of “bearing arms”, including the British Common law which we borrowed much of our laws from. That is what those briefs are for, to fill in blanks outside of the main questions that were addressed in the Heller brief.