Good point that there is a distinction between the quantity of cuteness (finding most of a population cute vs only a few individuals). Although part of it might be a cultural bias because cute dogs and hot people are given much more presentation in our society. Like watching a movie and nearly everyone is conventionally attractive. There are many dogs out there that aren't cute at all, but they aren't usually shown in posts/videos about cute dogs.

Regarding the evolutionary adaptation you were hinting at, I think the domestication syndrome makes it so that we see animals like dogs as partly infant-like. That is, bigger eyes, round features, etc. So maybe there is some trained response in us that reacts to those infant-like features? There is definitely some positive association because otherwise the domestication syndrome wouldn't be such an universal thing.

I'm not even trying to suggest any judgement, if anything I'm just lamenting something that for my entire lifetime I have not been able to relate to or understand in my peers, which makes me feel somehow lacking, I guess.

I get that. Like I said, I feel somewhat similar towards human babies. Although since I'm an aunt and more in contact with infants/small children, I now understand it a bit better. I think you would probably find dogs much cuter once you get to develop a relationship with one. A friend of mine has been sitting a dog for some months now (only once a week) and his behavior towards dogs has completely shifted. Before he thought they were annoying or unimportant, now he always points out cute dogs in his environment. And I think building a connection is really the magic of it all. I grew up with a dog and she was really like my sister. I felt much sadder about her death than about my grandparents' deaths, because I was closer to her than to them.