The corn in corn chips has undergone nixtamalization, which makes more of the nutrients available to humans.
As others have commented, no. 2 yellow field corn can be ground into cornmeal, and even without nixtamalization, it is certainly digestible by humans, it's just that nixtamalization makes important nutrients like niacin available.
I think it's the lack of nixtamalization that makes cornbread so nice and gritty and corn chips so nice and crunchy. Try Ottofile dent, if you can find it or grow it.
As others have commented, no. 2 yellow field corn can be ground into cornmeal, and even without nixtamalization, it is certainly digestible by humans, it's just that nixtamalization makes important nutrients like niacin available.