Why is Pablo Picasso considered a great artist, and why are his paintings admired so much?

The other answers are really good. Here is another comment:

There is a large painting by Picasso called "Guernica," which depicts the aftermath of the bombing of the town Guernica during the Spanish Civil War, where innocent civilians lost their lives. The painting occupies an entire wall and I had the chance to see it in New York when I was younger. Its enormous size, monochromatic palette of black, white, and gray, left a strong impression on me. I remember seeing it on multiple occasions.

Years later, I encountered the painting again after it had been relocated to Madrid. By that time, I had experienced living through a war, and it had a profound impact on me. "Guernica" managed to encapsulate the overwhelming feelings of being in a war: the chaos, the wrongness, the darkness, and the confusion. The twisted figures, fragmented shapes, and the anguished woman portrayed in the painting perfectly reflected my own emotional experiences.

Life itself is not always beautiful, and Picasso skillfully fused external form with inner content in "Guernica," creating a masterpiece that resonates deeply.