What are the positive shapes in the painting in the painting Marizy Sainte-Genevieve, Maurice Utrillo, 1910

The houses, buildings, and walls are all positive shapes in the painting.

your word would be isle.

isle is an island or peninsula especially a small one.

if you add the letter "a" you get aisle, which is a passage between 2 rows of something like chairs, shelves, or something else.