I learned on a SA Shrek. I was only given about 3 rounds at a time to work with though. And even then I was very closely watched. But I taught my kids on a single shot, bolt action. Patience is a good thing. Now both of them can shoot pretty well. My daughter especially shoots great.
You might want to consider a 22 wmr bolt action. It's a gun he will indeed keep for the rest of his life. If you do choose to go this route you can have your own marlin vs savage debate. They both are great guns.
Your son will love any first rifle he gets. I still have mine, a Remington model 582. I got in 1969, and will never part with it. My son and grand son will enjoy it at some point.