What is the first record we have that says "Hey, those apes sure look like us"? For that matter, what did explorers of various cultures first think when encountering chimps/gorillas/orangoutangs?
I believe the earliest surviving description of gorillas is an account by the Carthaginian explorer Hanno, who already describes them as people:
In its inmost recess was an island similar to that formerly described, which contained in like manner a lake with another island, inhabited by a rude description of people. The females were much more numerous than the males, and had rough skins: our interpreters called them Gorillae. We pursued but could take none of the males; they all escaped to the top of precipices, which they mounted with ease, and threw down stones; we took three of the females, but they made such violent struggles, biting and tearing their captors, that we killed them, and stripped off the skins, which we carried to Carthage: being out of provisions we could go no further.
hi.. you may be interested in a few previous posts
How did European explorers react to great apes when they first entered central Africa? - Ancient Egypt, Dutch explorers
What did people think of the anatomical and cognitive similarities between humans and apes before before evolution? - Hanno, Medieval Europe
Would the Greeks have known what monkeys were before Alexander's campaign in the east? - Ancient Greece, Egypt
Before Darwin, had much thought been put into the relatedness or similarity between humans and other apes? - Plato, Linnaeus
When did humans first suppose they had a common ancestor with monkeys? - Linnaeus
What did people in the past have to say about gorillas and other human-like primates? - Medieval Europe