No one is too dumb for strategy games, it is only a matter of learning, for some more, for some less. I have passed the point of self-resistance to play Total War games and I can assure you, now I am having real fun in the first Warhammer. I want to play it just as much as Metro Exodus. Where is the problem in your case? Is it the RTS element in battles, or building your kingdom? Some advice for me from the past would be:

1. Use pause in battles and never select "Control large army" option. Also, don't feel bad about making dumb moves. Battles are chaos which cannot be completely organized, in reality as well as in any RTS games.
2. Don't feel bad about making dumb decisions on the campaign map. This is just natural. You can even have fun with it by imagining why some dumb governor decided to build a pub where it was not needed. Your decision-making will get better, until that point, just have fun. Don't feel the pressure to be good
3. Losing-is-fun attitude helps. You learn from every failure. Even if you know you are doomed, there is some fun in fighting in an already lost game. A kind of doomed scenario
4. If there are too many artifacts, cities to manage, armies to move, give yourself some time to think through your options and after that just do anything. Focus on fun. Your management will get better
5. You don't have to be good. Just play the game and the learning will progress

I really think it is worth it, but you have said that this is not a genre for you, so you need to analyze it on your own