In the time before the renaissance, art was mostly a way to practice expensive religious devotion, like building a cathedral. Like most of medieval culture, the main focus was on the next life and man's devotion to it, so depicting the world as it is, wasn't really a necessity.
During the renaissance, art adopted mathematical precision, since the invention of the printing press meant that diagrams and maps could be consistently depicted the same, so accuracy became important for artists. This moved the subject of art from the spiritual to the real. Creating rules on things like proportion and perspective. This meant that artists became very interested in drawing the world around them. They went from custodians of a spiritual and religious culture to observers of nature, architects, naturalists, scientists etc.
From the renaissance, and this focus on the natural world artists begin depicting scenes of nature, and the Greco Roman Gods who were personifications of nature in this idealized way. People also adopt higher philosophies on life than the focus on spiritual guidance of the medieval world. From this enlightened thinking comes Baroque art, a way to idealized and exemplify the aesthetics of nature. Art and aesthetics are now an aesthetic component of the new enlightenment philosophies.
Then the subjects change from abstract ideals and nature to portraits of people. Now portraits had always been a way to flex on your peers, since art is expensive. But the amount of wealth people have now has become fucking insane. Since the long term effect of those maps and diagrams that are finally mathematically consistent in the renaissance is that suddenly the world can be navigated and that opens up trade. And from this mercantilism, land owners become insanely fucking wealthy. So now you can higher a baroque painter to depict how wealthy you are, by making YOU the idealized subject of his heightened aesthetic.
This is how we get to arrive at Rococo art.