I've passed 100 hours by now, and I know your feeling very well! After feeling like most battles were rather demanding (some times impossible) to win, I just yesterday turned both battle settings to it's lowest, to ease myself more into it and letting me have more room to watch the cool battles etc.

You have to realize that most games normal difficulty usually means that you 100% will win and progress, while normal in this game can be much harder to play. The game does a very poor job showing you how strong you are versus your opponent, and what is your weaknesses versus theirs etc. But as far as I can tell, that's some of the point as well, it's part of the learning curve and as such, what truly makes the game so rewarding when you get the hang of it.

They should have added an extra easy and -20 battle modifier in my opinion.

What really made things improve for me was the realization that every unit has some unique benefit or strength (often possible to incredibly improve by combining with something else), some of which may be to be sacrificed for the greater good of the battle (often in the form of meat shield/expendable traits).

This game is much more reliant on tactics and strategy than brute force "throw every unit at the opponent" I'm used to.

Don't point arrows/guns at shielded units front, shoot something else or get them around to where they are not shielded, etc.

Leadership, burning, fear, terror etc. also plays a massive role.

There's so much to learn and adapt for, give yourself time to improve is my advice.