There is no survival for us without hurting some other living organism. Even a purely vegan diet (which does not provide the complete nutrition we need) hurts plants and other critters that also want to eat those same plants or use them for shelter or whatever. So, I agree that we probably shouldn't feel too superior or different from other living things, but we also don't need to beat ourselves up for hurting other living things. We can't eat rocks.
Doesn’t mean we have to eat people or murdering animals. A rare person beats himself up for eating salad, but I promise you majority of people around you have various reservations about murdering and hurting animals and people. Growing up in some cultures and being fed abstract clean pieces of flesh just allows people to compartmentalize.
Also knowing that nothing on my plate was tortured for its entire existence on a factory farm is important to me. I still eat meat but it’s either meat I harvested personally or from a local farm where I can verify the living standards. As a consequence I eat significantly less meat. It’s entirely possible to opt out of the industrial factory farming method that abuses animals the entire time
B12 is generally the biggest concern. Vegans need to take vitamin supplements to get it. The B12 in those supplements is produced in factories doing bacterial fermentation
True herbivores have stomachs that can ferment B12 from the plants they eat. We do not
Another one can be iron, depending on your genes. There’s plenty of iron-rich vegetarian options, but heme iron in animal sources typically is absorbed at rates of ~40% while non-heme iron in plant sources is absorbed at 1-10% depending on the specific source. Non-heme iron absorption is also blocked by calcium and magnesium that compete for the same receptors. It’s not impossible to get enough iron in a vegan diet without supplementation, but it requires some careful planning of what sources you eat and how you cook it, and if you’re genetically predisposed to anemia it can be risky without monitoring your bloodwork.
You should certainly try to do the least amount of harm possible. We don't really understand what harm is in all cases. We don't fully understand the lived experience of a chicken or the lettuce plant we cut up or the rabbit that died because we ate his lettuce. You could really tie yourself in knots trying to figure out what is less harmful overall.
