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).