You really believe that the difference between “culture” and non-culture is seeing a statue with a penis or not? All that means is that you're either narrow-minded or dumb.
Art is human creativity. Culture is what people do.
People have penises, I think quite a lot of them do, and people will make art and culture out of sex because, quite frankly, it's fucking (excuse the pun) important.
Different cultures, even in 2023, deal with sex and nudity in different ways. I lived in Germany, on a hot summer's day you could go to the river and there'd be naked me. I even lived in Austria, and I went walking and wanted to sit down, and remembered a lake in an empty forest I'd been to when there was snow, I got there and it was packed, and there were some naked men sunbathing/hiding in some reeds or rushes. I couldn't see them from the bench(the last bench free) I was sat on, but some dude was trying to perv on them anyway from about 10 meters in front of me.
Saunas, both Germany and Austria do saunas, I do not. I don't like them clothed, and I've never been in one unclothed. But the Germanic and Scandinavians love their saunas and will be naked. The Austrias get angry at the Italians for going into saunas in their swimsuits. They say it's dirty.
You have FKK beaches in Europe, for Germans, mostly, to go nude on beaches.
They don't care, they don't find it sexual, they don't make a big deal out of it, they just do it.
Culture, it's culture because they do it and it's different to the US where, it seems, showing your ankle will get you criticized by some right winger (who'll be found naked and bound the week later, having paid for some man to "punish" him).
When David was made, it was part of the culture of that period, and that period is a VERY influential period in time.
Take DC, full of Greek/Roman style buildings. The Eagle for the US, taken from the symbols of power from that time and before.
It's culture, it's considered HIGH CULTURE (rather than culture v. no culture). You don't have to agree, but it is.