Even after some tries I was unable to find the “default” fonts used in the WordPress theme 2016 for body and headers. It would be nice to know this quickly from the customizer. The below doesn’t give any helpful information.
Found the information here: Review of WP 2016. Turns out it’s Montserrat for the Headings and Merriweather for body text. Merriweather was designed to be a text face that is pleasant to read on screens. Montserrat‘s inspiration are the old posters and signs in the traditional neighborhood of Buenos Aires called Montserrat.