You brought up neuroses, specifically the "neuroses of humanity". Since you are using this as a broad term to refer basically to everyone who is alive today, that carries, at the minimum, the flavor of a collective unconscious (a term I did introduce to the conversation), whereby since everyone is carrying individually the samskaras of their recent animal lives and you say this is collectively flavoring the "neuroses of humanity". A neuroses you imply that is either something new or somehow different now than it's been before (as if humanity's previous neuroses, aka samsara, was somehow better?).
Which is to say the neuroses that humans suffer from now as seeming individuals, not some sort of collective unconscious. If what I said came across that way, it was not my intention. I did not say this is new. Ignorance and lust are certainly not new features for humanity. What I am saying is that not everyone that has a human body right now necessarily has a fully developed human mind so it is natural that humans on the whole are taking on modes of being of the lower realms.
So I get the idea of how one's previous life carries forward, but the leap I'm struggling with is, unless you are a Buddha, how do you know from which realms etc those being born today are coming from? Not only do you state they are from the animal realm, but that they are from slaughtered animals. You cannot know that.
I don't know in the case of any *individual being* where they have come from by direct perception. However, that is not the only valid means of knowledge. You can reason based on the teachings. Beings that one kills one owes a debt to. There are few stronger actions than taking the life of a being. Given the scale of misery we as humans have been subjecting animals to in the last 60 years, there is no question that we are incurring a tremendous debt to the victims of slaughter. The karma of pretas and narakas is much more extreme and as the teachings illustrate countless times, it is much harder for them to escape from their realms.
You're projecting your own mind onto reality, which we all do, but that doesn't make your reality true. You're also making judgments on whether that is good or bad and whether "it" is different than it was before.
I am not projecting my mind onto reality. I am presenting a reasoning based on the teachings. Good or bad is irrelevant and another concept like the collective unconscious that I have not brought up in this discussion.
We have sutras, tantras and shastras. We have commentaries. We have access to teachers. Have you never asked yourself how it is that the human population has grown sixfold in 100 years? I don't believe humans (or any other being for that matter) are born as tabula rasa.
Also, the characteristics you are pointing to have been around in humanity for as long as we've had recorded history, at least from the time of the Agricultural/Neolithic Revolution. And certainly have been put into writing since Darwin and the whole concept of the survival of the fittest. Which is before this imagined influx of rebirths from the slaughtered animal realm.
If you read the teachings on the six realms from any school, it is always pointed out that while humans suffer most strongly from pride, they have all the other negative emotions within them. This does not invalidate that when large numbers of beings come from different realms, the balance can change. Look at how degraded things have become! Heck, Ayn Rand is even considered a writer and philosopher. If that isn't a sign of Kali Yuga, I don't know what is.