For the most part I actually agree. However, I personally don't feel Humanity's worst traits are our intrinsic and natural behavior. Just like how parenting cultivates ultimately how someone will grow up into society, that society then does the same. Communism tries to build a society that cultivates the best aspects, that provides to foster the sense of community that we often see following disasters and other crises. People who thinks our ills will be rid of or "fixed" are naïve and utopic. There will always be bad people and difficult challenges ahead of us, and a lot of communist writing specifically argues against trying to achieve a utopic ideal (because a Utopia is impossible, obviously).
"To me humans are simply animals, animals who learned to speak and think and then thought themselves better than everything else and smarter and capable of leaving behind their vassal roots as mere beasts to achieve perfect society."
I 100% agree on this front. Humans being merely animals that "think" better than the rest is pretty apt in how Communist theory describes us. We are but matter from which consciousness arises. Communist Theory is also very pro human and speaks to the unfathomable potential Humanity has in relation to how it can interact with the material.
"Feudalism wasn't borne as some sort of vile biblical ill, but instead was the inevitable conclusion to history and society up to that point, communism itself only exists because of the consequences of the industrial revolution"
This is actually almost verbatim stated in a lot of the newer texts. It's important to acknowledge that communism would not be possible without the infrastructure and industrial growth capitalism brought, and too many commies either forget or completely miss that (oft because they don't read any of the books). Communism is meant to be a Societal Epoc, just like Feudalism and Capitalism before it. It's also right to criticize the flaws of those systems, and how those systems often come to cannibalize themselves in the late stages of their existence.
"The thing is that I don't think it works on humans, maybe it'd work on robots or ants who don't value the self and only work towards the greater good, but humans are naturally selfish, very few people will sacrifice everything for complete strangers."
This is a whole can of worms I don't have the time to really dive into, but it benefits the rich for the common people to be at each others throats and in fear of each other. When the people are too busy fighting each other to notice you getting an anti-worker and anti-consumer bill passed, there tends to be too little outrage to make a difference. At the same time, these economic changes that put more money into the pockets of the rich make the common people work harder and more jobs to make ends meet. Hence the "I don't have the time or money to care." beer drinking, burger grilling brand of conservatism practiced by blue collar workers, of which I'm intimately familiar with.
"Communism was engineered in a lab by a bunch of economists who didn't take into account the human aspect of it"
This is the one part where I strictly disagree, especially on a factual basis. Communism was borne out of Marx's discussions and research with workers in the mid 1800s. In fact, there were proletariat uprisings and strikes fought on the ideals of communism before Marx and Engels codified it in writing. The Paris Commune was the big inspiration for this work and is constantly referenced in Marx and Engel's books on the subject. Communism is first and foremost a field of philosophy and should be treated as such, even if Marx's magnum opus is a work of economic genius that both sides draw from to this very day. (Das Kapital in case you can't remember the name).
I'll stop here as I don't have the time for anymore, but I genuinely appreciate the well articulated and honest argument. It makes me happy knowing there's intelligent people like you out there.