Hanno the Navigator thought that gorillas, at least, were people:
On the third day after our departure thence, having sailed by those streams of fire, we arrived at a bay called the Southern Horn[11]; at the bottom of which lay an island like the former, having a lake, and in this lake another island, full of savage people, the greater part of whom were women, whose bodies were hairy, and whom our interpreters called Gorillae. Though we pursued the men we could not seize any of them; but all fled from us, escaping over the precipices, and defending themselves with stones. Three women were however taken; but they attacked their conductors with their teeth and hands, and could not be prevailed upon to accompany us. Having killed them, we flayed them, and brought their skins with us to Carthage. We did not sail farther on, our provisions failing us.
The ape shows up in medieval life in several places, beginning in the early high middle ages. We find them in a handful of church sculptures. The dominant view is that apes represented some evil aspect of human character, some terrible flaw. This is suggested by correlations to some representations in early art from Iberian Islam and some hypothesizing of influence from Aesop's Fables, both of which entered western European culture just before the high middle ages.
Monkey representation really begins to take off later in manuscript marginalia. They are often doing human activities which never explained in the manuscript texts. We infer they acted as allegorical representations of aspects of human character and fate. The British Library's manuscript blog is always a fantastic source of thematic surveys, and they have one on monkeys playing bagpipes and gardening. It's hard for us to construct precise allegorical intentions, in part because monkeys aren't alone in representing human activity: rabbits, foxes, bears, dogs and cats all have their turns 'as humans'. Many of these allegories are lost to us, and may be highly personal or meaningful to a certain region or even a joke within a scriptorium. But we can see that western medieval peoples encountered the ape and recognized some correlation with humans.
Intriguingly, these monkeys show up in many late medieval manuscripts from Netherlands-Flemish territories - as with the BL webpage above. And a century later they show up in painting of Two Chained Monkeys by Pieter Breughel the elder. The city in the background of the painting is the great northern Renaissance merchant import port Antwerp, right in the middle of the Flemish-Netherlandish geography.
We're reading between the lines here, but allegory of human folly and fate in the medieval period seems to shift to metaphor in Breughel's chained monkeys. In the context of Breughel's other moral paintings, the abiding theory of this painting is that the monkeys represent some aspect of human ambition. The nut shells in the painting are often correlated to the Dutch expression "to go to court for the sake of a nut".
The monkey on the left in Breughel's painting looks directly at the viewer. Perhaps a challenge: we can feel in these representations a tension between the ape-as-itself and ape-as-human, reflecting the dichotomy of the Christian allegorical world view.
In Bahasa Malay the word "orang" means "man" or "person" and "utan" means "forest" - an "orangutan" is a forest-person.
For years, Western scientists thought stories of orangutans in Sumatra were of a type with bigfoot and yeti, a wild man who lived in the woods, half beast and half human.
There's still some controversy over a similar cryptid, orang-pendek, described by witnesses as an ape that's about 3 feet tall and walks on two legs. Because of the name, though (and since one has never been caught and identified), it gets more sensationally called things like "the forest hobbit of Sumatra".
That process - finding something mythological or fantastic that this unknown thing resembles - seems like a human universal. (See also Architeuthis dux and the kraken....)
It might also be worth pointing out that there is a movement within primatology today to reclassify great apes as a species of Homo (I think Homo sylvanus got suggested for chimpanzees). It's meeting quite a bit of resistance.
The movement is alluded to in this article on the personhood of apes by H. Lyn White Miles, which opens with the following historical quote on orangutans:
I still maintain, that his [the orang-utan] being possessed of the capacity of acquiring it [language], by having both the human intelligence and the organs of pronunciation, joined to the dispositions and affections of his mind, mild, gentle, and humane, is sufficient to denominate him a man.
Lord J. B. Monboddo, Of the Origin and Progress of Language, 1773
