Why do nonmetals make up almost everything

It is the most abundant

Explanation:

The four most abundant elements by mass in the human body are other nonmetals including oxygen (65%), carbon (18%), hydrogen (10%), and nitrogen (3%). The most abundant of the other nonmetals in the Earth's crust is oxygen which is the single most abundant element in the Earth's crust.

protein makes up the building blocks of organs, muscles, skin, hormones and pretty much everything that matters in your body.

some choices are:

peanut butter

seeds

eggs

yogurt

meats

fish

so pretty much meat, dairy, nuts, and grains.