I can provide a partial answer to this question relating to pubic hair on ancient statues, but I can't speak with any level of authority about medieval and Renaissance art. tl;dr: fashions changed and varied by gender and culture, body hair in ancient art does actually appear and there is evidence of grooming fashions, but there are issues of preservation and when it appears it may have symbolic purposes as well as representative ones.

I'd like to make three key if fairly obvious preliminary points. 1) body hair includes pubic hair and more general arm/leg/torso hair, the first appears more often than the second. 2) how and when body and pubic hair are shown is partly a gender issue. 3) grooming behaviours/norms varied through time and across cultures (sidenote that this may be particularly relevant in renaissance sculpture, which I believe modelled itself somewhat on ancient sculpture and may or may not have reflected gender norms)

I suspect you may be talking about body hair more broadly, which would be a fascinating question which I'd also love to learn about. Sadly I've never actually heard it discussed in much depth so I'm not sure I can speculate beyond saying that ancient statues were generally polychrome (painted), and it's entirely possible fine details like body hair were painted on (sculpture tends to work better at portraying really thick hair, especially in curls and braids than finer or sparser details, and this may have affected the artistic decisions of the sculptors).

I do also know that medieval beauty manuals called books of secrets survive which detail some medieval women's methods for chemically removing hair: Jill Burke at Edinburgh has a fascinating blog post about this (actually her whole blog is very much worth reading).

So onto the section of this question I feel more qualified to address: ancient art, and pubic hair. I'd like to qualify the information below by saying that I'm only a student, and the information below comes mostly not from independent research but from some of my undergraduate lecturers whose names I stupidly didn't note down. One may have been Bert Smith. I have the pictures to back up my argument saved to my computer: I'll try to upload them but I'm not good at Reddit, and I'm not sure how it's done.

The first thing I'd like to note is that ancient sexual norms are rather different to our own: in particular sex with and sexual attraction to rather young adolescents was normalised in ways that modern viewers may find disturbing/distasteful. I want to make it really clear that I'm not justifying this, but I do think it's relevant to any discussion of ancient nudes so I'm trying to be factual and avoid anachronistic moralising. Girls were married young to much older men, I believe often shortly after puberty (14-16 often, but you should bear in mind that puberty often starts later and progresses slower when people are underfed, which was common in the ancient world) and the prostitutes and escorts we see on vases probably entered the workforce (if that's an appropriate term) at a similar age. Pederastic relationships meanwhile were a rite of passage among the elites of many (perhaps most) Greek city states; indeed these relationships between a teenage eromenos and an adult erastes were I believe the most recognised and accepted type of homosexual relationship in ancient Greece.

The relevance is that many of the "beautiful nudes" produced are probably of people at what the Greeks considered the high point of human desirability, ie teens and maybe early early adulthood. I believe this is also an age group with generally less body and pubic hair than older adults, especially in men, which would probably affect the appearance of body hair in nude art, which tends to present ideals. Greek literature, like the passage or Aristophanes I mention below, often disparagingly describes older men as hairy and goatish (the second of which of course has sexual as well as physical connotations), implying firstly that body hair was thought of as unattractive (at least to adult men) and that it was a normal or stereotypical feature of older men's bodies. The key feature of these older male bodies is that within Greek sexual mores they belong to the desirers rather than the desired. In art, except comic/grotesque art they are more frequently shown clothed than young bodies.

Women are rarely shown with body hair of any kind in ancient Greek and Roman sculpture. It may be relevant here that they rarely actually show "real" women naked at all: naked female bodies tend to be at least nominally divine figures like Aphrodite, and there may be some kind of idealisation going on (which is itself interesting as evidence for beauty ideals if not of everyday life). We do have evidence that female pubic hair removal may have been widespread in classical Athens: a comic scene in Aristophanes Thesmophoriazusae ("Women at the Thesmophoria", in which men sneak into a women only festival) has a man singeing off his pubes in preparation for his disguise, and the implication seems to be that this is a common female behaviour, and uncommon for men. (It's also apparently painful, which I can entirely believe). We do however also have occasional images of pubic hair on women on vases, especially on maenads (the wild female followers of Dionysus). One interpretation I've heard is that pubic hair would be associated with sexuality: this is possible, but even quite NSFW vase paintings depicting sex scenes and so forth rarely show much pubic hair on women: I would prefer to propose that grooming is associated with civilization, and full bush with a certain wildness. A very faint and small triangle isn't infrequent though. Like today there might also be a selection bias: certain social groups of women, such as those shown in said sex scenes (who are likely to be sex workers), might be more likely to engage in elaborate grooming than a secluded housewife, and might also be more likely to pose for artists. I'd also like to caution that this does not necessarily represent real life appearances - you may have noticed for example that Greek art tends to show men with fairly small and dicks. This seems to have been an understood symbol of civilization and sexual/emotional continence (satyrs, in contrast, are downright priapic as a rule) and it would not be justified to interpret it as evidence that ancient men were unusually small.

Men are more often shown naked: Greece was a very homosocial culture, and public male nudity was frequent in real life, both as the defacto option for the very poor (Jill Burke has an interesting blog post about parallels in Renaissance Italy) and as the athleisure option of choice in communal gyms. This has an interesting effect: you can basically track changing fashions in manscaping though depictions on Greek art, in particular "kouros" sculptures of young men. (Once again the caveat that art tends to show ideals applies, but here we can see the ideals changing in a way which probably reflects fashion, and so is likely to reflect real life. In particular the widespread social nudity at the gymnasia makes it likely that grooming fashions would spread). My lecturers argued that broadly speaking, paint traces on archaic kouros statues (especially those of the orientalising period) tend to show fairly elaborately sculpted pubic hair, plucked/singed/shaved into ornamental shapes like "fish scales" like that shown clearly on the Sarpedon krater here, while we see a shift after the Persian wars (the so called classical period) towards full bush, such as that on the Rialto bronzes, while ornamental shapes reappear a little but never fully take over in the Hellenistic era.

These lecturers also argued that this change reflected a shift towards an aesthetic of austerity more broadly after the war. This seems plausible but I don't feel qualified to assess it as I've not read about this elsewhere, and it might just be his pet theory. I would note that the Rialto bronzes show rather older men than archaic kouroi tend to, which may be relevant, and also that classical and Hellenistic statues with minimal pubes survive. If painted on pubes were customary during this period too there may be an issue of preservation, and this may apply to female statues too. However, red figure vases from this period (which don't suffer the same issues of preservation) often show men without pubic hair or with heavily groomed pubic hair analogous to the tiny triangles most common when we see women's pubic hair on vases. Overall however the evidence available implies that we can get some kind of picture of grooming norms or ideals in the ancient world from art, especially among young men, and it seems like some level of more or less extensive landscaping was very common in ancient beauty norms.