I don’t know much about how they prepared food in the Americas in the Upper Paleolithic(*), but I’m pretty sure they ate anything and everything they could catch, forage, or hunt, and that was deemed edible. And that they didn’t waste much, and tried to conserve food for later use. The traditional diet of inuits should give an indication of which parts of which animals were/are edible in the northermost parts of the Americas, or at the very least the preferred parts.
Personally, I’ve eaten lots of body parts other than prime cuts of diverse animals, such as the stomach (tripe), kidneys, tongue, heart, bone marrow, blubber, and blood, either as is, or further processed. And I’ve had diverse parts of fish, like the stomach, swim bladder, liver, roe, heart, skin, and brains. And I’ve tried grubs and insects. If prepared correctly, most/all of these animal/fish body parts can be quite delicious. And there is a reason these parts are included in the traditional diets of people around the world: because they can be eaten, and if you are hungry enough or have barely just enough food to stay alive, you cannot afford to throw it away, and you will gladly ignore the initial “yuck” factor.
(*) I’m pretty sure that’s not what you meant by “the early settlers”, but that’s how I choose to interpret it.
Edit: Oh, and regarding vegetarianism or veganism: If you elect to subsist only on plants and plant derived foods (plus eggs, honey, and dairy for vegetarians) - great, that’s your choice. But such a diet is really not an option some places. Some places just have a too hostile climate to grow plants that can deliver enough calories, protein, and fat to keep you alive. So you are forced to go for a diet that is at least partly based on animals and/or fish. Vegetarianism or veganism at large is a modern kind of luxury only made possible by modern agriculture, and requires modern forms of mass distribution. It is only in certain parts of the world that you can get by growing your own selection of plants (or sourcing them locally) that will deliver the needed nutritional groups - proteins, fat, and carbohydrates - in sufficient amounts.