It's not true that by weight chicken breast has higher concentration of protein than beans.
100g of raw beans, or 100g of raw lentils, has more grams of protein than a chicken breast. 100g of raw soybeans has more grams of protein than same amount of beef.
Of course, "raw" is the catch word, because when cooked, beans/lentils fill with water and then you might claim that concentration has been lowered but the amount of protein stays the same (nothing is lost by cooking).
100g of raw beans, or 100g of raw lentils, has more grams of protein than a chicken breast. 100g of raw soybeans has more grams of protein than same amount of beef.
Of course, "raw" is the catch word, because when cooked, beans/lentils fill with water and then you might claim that concentration has been lowered but the amount of protein stays the same (nothing is lost by cooking).