To your last point, I think it's a natural progression of our species. We realize that we were stupid animals like them at one point, and look at us now? Technically they are just earlier in their evolutionary chain (some of them, some species due to the way evolution played out will never be a fully intelligent species like humans, but we know some of them are already well on their way) so are we really just eating what would just be babies in terms of intelligence?

Where does the line get drawn, how intelligent does something have to be before it seems like just as much of a crime as eating a human child? We already know there are species, that we currently eat, that have the intellgence and capacity to learn similar to that of Human toddlers! Is that not something that gives you at least pause? Do you not at least have the thought that: "This animal I'm about to eat scientifically seems like they are just as capable of cognitive thinking and complex emotions and attachments as a toddler, am I okay with this?" What's your answer to that question? For me, it's not black and white, it's not a simple yes or no answer, and I feel like most people who believe what they say about the intelligence of these creatures must be similar.

Then to top it off, through animal and plant husbandry, factory farming, and automation of food production we are rapidly approaching a point where we might not need to eat these intelligent species to survive, due to our ability to grow our own food, even meat now! One day in the future, we realistically can envision a world where everything we eat is grown in some capacity. When we reach that point, shouldn't we ask that question again? When the needs of our species can be met through technology, what is our responsibility to the lives of these creatures at this point? When does it become pointless killing of living beings? It's a genuine question.

Me personally, I don't think we are quite at the evolutionary point where we can sustain our society without the products of agriculture as they currently stand, so I think it's unrealistic to try to force everyone to stop eating animal meat in the short term. I think it's a great philosophical question we should keep asking and keep revisiting, because I think one day in the future the answer will eventually change to a world where we might change the way we view animals. And in the meantime, I'm all for legislation to try to make the process of cultivating animal products as ethical and harmless to them as possible, I feel like that's the least I can do for the species while we use them as a battery to fuel human evolution.