Yeah, hey at least he is eating. You can build on that!
My son is 15 months and has gone through various phased where he will only eat pureed food, only eat jars, or whatever. I can usually get him out of it, it it takes practice. And I keep forgetting to make the effort to buy varied stuff! I'm not a very good cook either, and I found a book that really helped me was The First-Time Cook by Sophie Grigson. It's really friendly and gets you feeling like anyone can learn, it doesn't matter when, you just start with the basics and build up from there over time. A bit like what you need to do with your DS, I suppose.
Mixing a little home cooked food into the jars in a great idea, and gradually increase the percentage until he is eating all home cooked. You will get there. Also, don't stress about food in front of him, even if you feel like tearing your hair out in private. Be happy and calm about his eating, praise him when he finishes his meal and tell him what a good boy he is, and give him different finger foods to play with so he gets more used to different tastes even if he doesn't eat them for a while. Mine likes bread sticks snapped in half, and sultanas. Oh, and pasta twirls, so long as they have pesto on. A few months ago, it would have been laughable he would eat anything like that. If you can get yours onto pasta that he can pick up and eat himself, you can blend some veg like peas or spinach etc and mix a bit through the pasta. Then, he has just eaten fresh home cooked veg!
Remember that he won't be eating jars forever, at some point he will want to try the food on your plate and love being praised for eating like a big boy! Then he won't need to have separate food, he can just have what you're having.
Good luck, I know how guilt-making it is when your child is a tricky eater..
x