Evolution does not have a big table where it draws organisms such as Ninja turtles or Marvel Doberman Pinscher DP Avengers shirt, hoodie, sweater and v-neck t-shirt. Evolution molds organisms based on structures and features that are already there. In the case of humans, we are primates and there isn't a single primate that is armored. There are a few armored mammals belonging to the Order Edentata, such as armadillos. And their armor is protective only to a certain degree, as anybody who has seen a dog catch an armadillo can attest (I had the misfortune of seeing a Doberman dispatch an armadillo in seconds, some decades back, in my home country).
