Imagine what humans would look like to beings like that. I remember one sociobiologist saying something like humans are apes who started living like ants, take a step back, picture that from the perspective of an intelligent vaguely ape-like being that didn't, couldn't make that transition, and think about how weird and scary and mind-blowing it might look to them, and of course it would be a source of great power to civilized humans, power that beings constitutionally incapable of civilization could never acquire.
I mean, I would say that our own species can't really conceive of it either; that there's an extent to which human civilisation is itself eldritch to us as humans. Like our ability to live in a big globalised society isn't because we can comprehend what that means, but because we can sort of mute out the hundreds of thousands of humans around us we don't know, invent stories to justify the world around ourselves and hyperspecialise within a massive system that's way beyond our individual comprehension. Like we're very much still using those mental systems where we live in tiny tribes, I think, and my view would be that human success has a lot more to do with emergent qualities of our interactions in that large society than it does about ourselves as individuals. Humanity is already eldritch; deeply so, and encountering this as a human can be very disturbing.
Anyway, I agree that we're definitely even more eldritch to animals and that thinking about that is an interesting way to think about the whole concept of alienness in general. I wrote a thing about this a while back in the context of Jeff VanderMeer's Annihilation, the novel rather than the film which seemed like it was about something else entirely.