It sounds to me like the AI is challenging.
The game is supposed to present a challenge. Even many of us whose primary job was playing the game still had to consider each random encounter carefully, and yeah, sometimes we died. Sometimes we died horribly. In every single instance though, perseverance ended up paying off. Slow down. Pause and play, choose each action carefully. Focus fire (press + to select the whole party) on the enemy who is the biggest threat to you, or the easiest to kill and get out of the way. Use your poultices and spells liberally.
The game is not easy, but rest assured that you are in good company in terms of people who have died over and over on a seemingly inconsequential encounter. Once it all clicks for you I think you will appreciate that the combat in the game takes actual strategy and full use of your party into account. Feel free to send any specific questions you might have to me in a PM, and I will do my best to lend a hand.