When you get on solid foods I found seafood by far what settled the easiest and was high on protein. Raw large deveined shrimp, leave the shells on as to not crisp up the skin and keep it moist. 1/4 stick of butter with some minced garlic and voila. Simple, tasty and goes down and settles in the stomach nicely. Cream of wheat has a variety of flavors in the morning. Sugar Free Pudding, Jello, or fudge pop if you crave a guilty snack. Avoid sugar and corn syrup. My freezer is stocked with shrimp, mussels, clams variety of fish and pork primarily. Chicken and beef are out for me for awhile. Mussels seem to be in good supply since right now and while I live in Ranch Country, fresh is not so easy to come by. But 2 for $7 on these makes a quick lunch in my busy schedule possible. I've also loaded up on some canned mussels to take with in the car when I have to drive a distance rather than hitting gas stations. A lot of the enjoyment is rediscovering food and trying new things.
For cooking basics I would suggest a good set of cutlery like Henkel or Wustof, get yourself some decent cookware like Cuisinart, All Clad (Staying away from all non-stick but maybe a single skillet) also pickup a cast Iron like, lodge, Field or Stargazer. Look at the forums or Facebook groups for owners of those products and you can find some good ideas. Look at the food forum here for recipes you can try. I post some trying simple ingredients to get new foods one may not ever think of trying otherwise. I personally looked at cooking as a hobby after investing in good kitchen tools. In a way it's like a gym membership that you pay for so you have to get up and use it because of the cost to you. Learn how to take care of those tools ( How to properly sharpen cutlery, clean stuck on gunk on pans, treat cast iron...) The more you learn about those tools the better and faster cook you become. I've gotten good enough now that most restaurants turn me off (too sweet, too salty, too buttery, overcooked, undercooked etc)
You can find a passion for food and cooking great tasting dishes I find there are many SE Asian dishes utilize fish and pork and are very tasty. Pho soup for example is a Vietnamese beef bone broth soup typically with shrimp, beef, pork, fish balls or squid as optional proteins to add. The broth is crazy high on protein and would encourage anyone to try it in a restaurant as it is usually not very expensive, great quality ingredients and they serve a lot of it to last several meals. My wife being a Filipina, we cook a lot of Philippine dishes which have a lot of Asian and Spanish flair. Cut the rice out to start and you have a nice dish of proteins, veggies and flavor.
I like to choose a different ethnicity and explore dishes from different nations. IE: Africa, Mediterranean, Russian, German, Greece, Norwegian, Mexico, Chile etc. You can quickly find dishes online that may be easy to make and within your diet (I always pay attention to how high the reviews are and how many reviews there are) If your fortunate you might even find a restaurant nearby that you can go try the dish first.
Here are the mussels I mentioned previously. I prefer to make everything myself so I know what exactly goes into my food, but in a pinch, it's better than alternatives.