I imagine if someone built Instagram for ancient Greek art and analysed it they could rediscover things like the Golden Ratio. And those Doric columns... all the same.
And with photography much of it isn't mimicry per se so much as the fact that humans find a lot of similar things interesting even if they pay no attention to other people's artwork at all. Even if entirely uninterested in other people's travel shots, people often find the rowing boat trip they took with their partner interesting enough to record a picture of their partner taken from said rowing boat, and so we end up with a lot of shots of partners sitting in the prow which can't really not be compositionally similar to other shots of other partners sitting in other boats on other rivers.
And with photography much of it isn't mimicry per se so much as the fact that humans find a lot of similar things interesting even if they pay no attention to other people's artwork at all. Even if entirely uninterested in other people's travel shots, people often find the rowing boat trip they took with their partner interesting enough to record a picture of their partner taken from said rowing boat, and so we end up with a lot of shots of partners sitting in the prow which can't really not be compositionally similar to other shots of other partners sitting in other boats on other rivers.