My dad would only allow me to have a shotgun for my first "real" firearm. His reason was safety. Yes, he did teach me all the safety rules and he wasn't afraid to remind me of them with his boot. Yet, he also knew that as a young shooter with a new "toy", youthful excitement sometimes overrode common sense.
With a shotgun using birdshot, there is less down range danger. Birdshot has a very limited long range danger. A .22 rifle is capable of hurting or killing someone much further.
I do think that shotguns make an ideal first gun.