2 books
Little Biographies for Bright Minds is a 2-book series for ages 0–9 by Naibe Reynoso. Each book stands alone — start anywhere.
Start anywhere — each book stands alone.
That said, Inspirational Leaders: 11 Men from Latin America Who Changed the World and Counting Piggies, Cochinitos Contando are great first picks.
No particular order needed — browse and pick what catches your eye.