Raw fruits and vegetables are good, human beings have the ability to digest it.
Once humans shifted to agriculture, we started making denser foods like grains. Grains were initially used only to feed cattle, and not for human consumption. It entered the human diet only about 6000 years back. Due to population pressure, grains then became a large part of our diet.
For optimal health, reduce grains in the diet. There is a huge amount of time spent on debating why Ragi or Quinoa is better than rice or wheat. These kinds of debates are needless if you anyway decide to reduce grains in your diet.
If you anyway have grains, then remember the following. In case you have a lot of inexplicable health problems or allergies, IBS, etc the first thing to drop from the diet is wheat. Wheat has undergone so much modification in the last two thousand years that the modern version has become a problem. You can try "emmer wheat / jave godi" , that may work for you.
Milk is in general not required for the human body. Eliminating milk is a healthy option. However, the vegans have it all wrong. Butter, ghee, curd and buttermilk are good for health, extremely good in fact. The vegans, in avoiding these, are throwing out the baby with the bathwater.
Naturopathy is generally in favour of raw foods. Ayurveda however typically recommends light cooking. When it comes to cooking, heating in the presence of water or steam is better than dry heat, since the yang of fire is balanced with the yin of water.
Rava, Poha, Sabudana, noodles, pasta, are all "processed" foods. They are made from rice or wheat after boiling, heating, dunking, rolling, flattening, etc, processes. In today's parlance, this is not what we refer to when we say "processed" foods.
The rice that is milled in the rice mill is processed in a manner of speaking. The more the "polish" the less the nutrients that remain. However, this is not a major concern for two reasons. (1) I do not depend on rice for my main nutritional needs, for that I have vegetables, fruits and spices. (2) In any case, rice or any kind of grains are not great for health.
Best not to worry about how much processing the rice has undergone, and try to keep progressively reducing the amount of all grains in your diet.
With all these caveats in place, now remember that processed foods are extremely, extremely bad for health. When we say processed food, a short and sweet definition is: any food that is made in a factory. As to the reasons why processed foods are bad for health, those can fill a book.
Rather than getting into huge debates on what constitutes "processing", to what extent is processed food ok, which processed foods are ok, or into semantical arguments on the definition of processing, it is best to understand the spirit of what is being said, the broad contours of what foods are good, and to maintain an eighty twenty principle. So long as eighty percent of the food you eat is "good", the body can handle the other twenty percent.
On second thoughts, make it ninety ten.