Poetry in general can be seen to owe its existence to two causes, and these are rooted in nature. First, there is man's natural propensity, from childhood onwards, to engage in mimetic activity (and this distinguishes man from other creatures, that he is thoroughly mimetic and through mimesis takes his first steps in understanding). Second, there is the pleasure which all men take in mimetic objects.
Let's take a look at the meaning of Mimetic-
"Mimesis is a critical and philosophical term that carries a wide range of meanings, which include imitation, representation, mimicry, imitatio, receptivity, nonsensuous similarity, the act of resembling, the act of expression, and the presentation of the self." -https://en.wikipedia.org/wiki/Mimesis
When we are children, we often learn from observing others and imitating their actions, which is why it's so funny to see a toddler wearing their parent's shoes or sunglasses. Through these imitations and people's reactions to them, we develop an understanding of things which we draw upon throughout our lives, some positive and some negative.
Sometimes these experiences have a major impact on our lives, which is what inspires one to write a poem and the appreciation we have to observe and learn from other's perspectives gives reason to read poetry and share our own.