I don't mind, that the pictures are only accompanied by their title. That's enough. Watching them with your child you don't need anything more. Kid only can absorb so much. You can sit together, look at details and have a talk. Goya mostly painted court people, so talk about courtly things. Poor queen's ridiculous dress, how children on the portraits wear same stuff as grownups, as soon as possible, you can play games who spots more of what we use today or on which portrait a duchess of Alba is younger, tell them of Maja's naughty portrait, without clothing, just have fun. You might touch more serious topics, for example showing them the wedding on the street, where it can be observed that black citizens were treated with respect and equality. Whatever lesson you feel you can give. Your child will absorb everything with ease and without boredom.
One thing, though. Many reviewers of Stanley Cesar's collections are frustrated with the tiny size of the pictures. You need to make an effort to learn to use your kindle. On mine, you have to quickly tap two times ON THE PICTURE YOU'RE VIEWING. That will open the big size of that picture, that not only is big enough to look at, but also allows you to move it around and stretch to make some details bigger. Once you're done you tap the X in the upper right corner and go back to your book, to turn to the other page.
Overall, great books for the purpose. Reasonable price, too. If, however money IS an object, with patience you can get many of those books on their free promotion. Author is generous that way.