Difficulty (The Witcher 3: Wild Hunt)

Why is the game so difficult. I put the plot and the fight.
And he couldn’t kill the corpse-eaters who exploded 6-7 times, by chance he killed 8 times and then almost zero life.
The bandits near the fortune teller who is a lover of sheep is similar, 2 crossbowmen immediately no longer allow anything to be done, it’s also hell with a double counterattack 100%.
Then this Igosha, he killed him, he mutated so that HP almost does not merge with him.

It feels like there should be a second player or bot to help.