Rice, breads, and noodles do make up a very large percentage of many people's diets, especially when you're in poverty.
Not just rice and wheat, but also including oats, barley, rye, maize, quinoa, potatoes, yams, manioc (a.k.a. cassava, yuca), taro, plantains, soybeans, peas, lentils, chickpeas, beans, etc.
Reliance on staples is the main reason that agricultural societies tend to have substantially shorter stature, shorter life expectancy, and more health problems than hunter–gatherer societies.
In recent times, the biggest problem is sugar though. Modern people consume ridiculous quantities of refined sugar in processed foods, fast restaurant food, soda and fruit juice, etc. Consuming large quantities of alcohol also isn’t helping anything.