I agree with everything that you said. But for a youngster, for the first gun I would start with a .22 single shot, bolt action, or lever action. Not a semi-auto.
Following along those same lines, for hunting I would not suggest a semi-auto. Not for their first hunting rifle.
The parent-child building of an AR would be an excellent project. My son actually helped me build my first AR.
What aspect of semi-auto did you want to avoid?
You can always load just a single round.
My eight-year-old grandson knows the safety rules and knows how to unload a magazine-fed, semi-auto handgun. He's ready for his first firing range experience which I hope to supply in a couple of weeks.
Nice. I wonder if there is an easy way (or a tool) to install the hammer. I have found that to be a very awkward process requiring quite a bit of hand strength.