Controversial question - what made human female breasts standalone objects of sexual desire?

I've never seen a breast stand alone. They usually comes in pairs.

Big titties reassure she can feed your offspring

They’re beautiful. 🤷‍♂

I know it’s crazy, but men love them. Doesn’t matter how many times we see them.

That's exactly why... they're hard to hide because of their location - and they stick right out.

Are you asking why they're fetishized? Or why are breasts are sexualized?
First - anything, and I mean anything can be an object of a fetish. Yes humans are that gross.
Second, I guess society? Their function is feed babies and signal fertility.

If men had to live with them in the heat of the summer, they would think differently…

I think apart from looking at the face breast size is another thing men and women look at.

Probably because on an evolutionary level, we associate big boobs with the ability to nurture children. Similar to how wide hips meant a woman had a better chance of surviving childbirth.

Really? So breast admirers will not be able to tell you the color of a woman's eyes, if she's stacked and they're spilling out? Kind of like a decapitated bust-only of Venus de Milo?