It was already mentioned in other threads, but you can find valuable insights in the AIP (autoimmune protocol) diet.
Its main principle is that you first eliminate as many foods as possible that are known to cause issues for people (e.g. due to inflammation, autoimmune response) and then you slowly introduce more foods and see how your body reacts.
I recently started following a similar approach in order to try to address some health issues and also to learn more about my body. In my case I'm leaning more towards the carnivore diet with occasional additions of foods allowed in AIP.
In case anyone is curious about the carnivore diet, I found these YouTube channels to contain good content on this topic: KenDBerryMD, Paul Saladino (CarnivoreMD).
I also enjoyed this discussion: https://youtu.be/Xgokvp5bfNg
It's easy to stumble upon conflicting information when it comes to nutrition, but I find that just being exposed to more options (rather than eating what everyone eats by default) can give you an opportunity to make the decisions that make sense to you.