I see I'm too late to recommend a rifle for you. I'm still going to post my choice for an "all around" beginner rifle that will never be outgrown just in case someone else happens on this thread.
I'm going to be different from all the other posters. My son started out with a Chipmunk bolt action because his Grandpa got him one for Christmas. I was very dissapointed with it. It has an awful trigger. The cocking mechanism is hard for small kids to operate unless it is squeaky clean. After shooting a handful of cartridges, the grit builds up and a small kid will end up doing dangerous things to try to cock it. The rear peep sight is way too big making it hard to shoot accurately, especially with the short sight radius. It is such a small gun, it will be outgrown very, very quickly. I would not recommend a Chipmunk as anybody's first rifle.
My recommendation is actually something between a bolt action and a semi-auto. It's the HENRY LEVER ACTION. I would make a different recommendation for CMP competition, but since you've already made your choice to take care of that, and nobody else has recommended this particular rifle, I'll go ahead and talk about it a little because it deserves some attention.
Just FYI, I have a Ruger 10/22 like many that have posted here, but I'm not fond of the trigger, nor did I want my son handling a semi-auto at a young an age. At the same time, I wanted a rifle he could grow into, and that would be as useful and fun in twenty years as it is now. The Henry Lever Action fits the bill. The Henry's price runs about $150-160 locally, which is less than what a 10/22 costs in this area. There is a youth version of the Henry also, but there isn't enough difference in weight and trigger reach to fool with it. The regular Henry is a fine choice. Here are the reasons why I chose it.
1. It has a sweeeeeeeeeet trigger. It makes the 10/22 trigger feel like the worst cap gun ever to hit a toy store. No need for fancy Voltsquartsen trigger assemblies.
2. It is very accurate. I like rubbing it in on my son by shooting the numbers out of his targets.
3. Safety. It isn't semi-auto, yet it can be cycled faster than a regular bolt action by most people if needed (a bunch faster for us left handed folks). Some people like to argue that a kid will be less safe with a bolt or lever because he loses his muzzle awareness while chambering a new round. I think an autoloader is less safe for a kid, especially if he/she becomes excited about the last shot he just made. He may lose muzzle awareness and forget to put the rifle on safe...which isn't good with a live round in the chamber. Bolts and Levers are the way to go with young kids as far as I'm concerned.
4. It has a tube fed mag that holds 15 rounds instead of a max of 10 rounds in a removable mag. I actually like the tube mag better for normal shooting. 10/22 rotary mags are good, but they occasionally need to be cleaned when using dirty bulk ammo....which leads to number 5.
5. It never fails to cycle and go bang...Ever...For any reason. No light primer strikes. No jams. No failure to feed. If it doesn't go bang, you're out of ammo or your ammo is defective!
6. Ergonomics for kids and grownups. The stock is a little shorter than most bolt stocks and it isn't heavy. It's great for young shooters, yet the stock isn't so short to be uncomfortable for an adult. I'm 6'2" and have no trouble shooting the little Henry.
7. Lever actions are different than what you usually see in the woods or the range, and they are fun to shoot.
8. Did I mention the little bugger is accurate? It is deadly accurate even with the cheap bulk Federal ammo I normally use. That goes back to why number 5 is important. You can shoot the cheapest, nastiest ammo you like, even shorts and specialty ammo along with the high dollar stuff. It eats it all and never burps.
9. Grownups love shooting it too. I haven't shot my 10/22 a single time since he got his rifle...I'm afraid one of these days he won't want me using his any more and I'll have to buy one for myself. Maybe that's actually a disadvantage...you don't want to have to fight with your kid on who gets to shoot the Henry.
10. You get to spread the wealth around. Everybody thinks Ruger, Marlin, and Remington, Savage, and Winchester when it comes to .22's, and usually in that order. Give the little guys at Henry some of your hard earned cash and keep as many firearms manufacturers in business as possible. If your Henry shoots as well as my son's, you won't be dissapointed.
11. Wally World carries them if you don't have a local mom and pop gun shop. (My local shop matched Wally World's price, but don't count on that happening with most guns. He was even nice enough to tell me he couldn't compete with WW on Marlin rifles and that I should go there for the best prices if I wanted a Marlin...he's a good guy.) Support your mom and pop shop if possible!
12. The wood is very nice looking American Walnut. It has a real stock buttplate instead of the cheap plastic strip modern 10/22's have. It works hard while looking good!
13. If you've ever cycled a Ruger lever action, you will note that it is clunky and almost toyish. The Henry's action is baby's butt smooth. It feels solid, and gives confidence.
14. The front post sight is hooded for protection. It won't get knocked around like a naked sight. It also helps give it that wild, wild west look.
15. Grooved receiver for a scope...if you really want a scope. I like to take the little Henry to the range with open sights and outshoot guys with scoped 10/22's. It is inherently more accurate than a stock 10/22 and its trigger is so much better that it lets me shoot better than the 10/22 guys (remember I have a 10/22 and I like it, but the Henry trigger is that much better). When I hear a 10/22 guy talk about his Volquartsen trigger and bull barrel, I start grinning and have myself some fun. I don't always beat them, but I always make them sweat until we start shooting at the longer range stuff. My eyes are still very good, but it's hard to beat any scoped rifle when your target is far enough away to be completely covered by the bead.
16. Price. They are as cheap or cheaper than a 10/22 according to where you live and if there's any competiton to keep prices reasonable. I dare you to find a rifle in that price range that's more accurate, I dare you!
Now for the disadvantages.
1. It has a blued barrel which means it needs to be wiped down after handling. That's not necessarily a bad thing as it teaches kids to be responsible for their property and you can teach them safe firearms handling and mechanical aspects of firearms during the short and quick cleaning sessions.
2. The receiver is painted, not blued so it doesn't perfectly match the blued barrel. It still looks nice, but as with any painted surface, it will eventually scratch or chip.
3. No classic safety. This isn't really a disadvantage unless the parent/teacher isn't familiar with oppen hammer firearms. If you are unfamiliar, teach yourself the ins and outs of the Henry before presenting it to your child, or have someone who is experienced give father and son instruction.
4. Loading single rounds directly in the chamber is a bit of a pain, but no worse than any semi-auto.
5. If you like accessories and making your rifle look like it belongs on a battlefield, get a 10/22. You won't find aftermarket doo-dads for the Henry. Then again, you don't need any. It's a straight shooter out of the box, it has a great trigger, and it's supposed to look like a classic lever action, not an M-14!
This is obviously my opinion and YMMV...have fun!
https://www.henryrepeating.com/leveraction.cfm
tim