Tangentially related, but I stopped being able to eat
beef and pork around the age 20 or so. In my case the doctor diagnosed IBS, which as far as I can tell is a catchall for you shouldn't eat it because it makes you feel unwell. The result is I have a long history of not eating pork and beef, so my alternatives might work for you as well.
Took a while but I don't miss either anymore. I eat a lot of chicken and fish, especially sardines, salmon, mackeral, various "white fish" like pollock and cod, but also stuff you don't see in the US like amberjack, bonito, pacific saury, freshwater eel, and tons of others I can't think of right now.
I also like other seafoods like shrimp, scallops, oysters, octopus, squid, and others.
Seafood is a spectacular realm of culinary creativity and the joys of it are endless. It just depends on what you have access to.
As far as fowl go, duck is a favorite. I used to eat a lot of turkey when I was in the US, but it's not produced locally. I've enjoyed pheasant and quail, but I can't say I prefer them to chicken, turkey or duck. Though quail eggs, while small, are delightful, especially when prepared in my favorite sushi: tsukimi natto gunkan
I've also learned to enjoy a variety of beans, seeds, grains, and pseudo grains for nutritional variety. Hummus is a wonderful way to get bean protein.