science has always existed as long as man has been curious about the world around him. Right back to cavemen who recognised the medicinal properties of herbs. The English word “scientist” is a relatively new word, introduced in 1834 by a Cambridge philosopher William Whewell who defined it as “someone who studies the physical and natural world through observation and experiment” ?
As Karen said, science has always existed. But how humans have researched science has changed over the centuries.
The father of modern science (the man who pretty much came up with the scientific method) and also the father of modern astronomy is Galileo Galilei. But he didn’t invent science. He just came up with a way for us to study science in a new way.
I think you can go back as far as pre-history! For example archeologists sometimes find human skulls with a hole in them. Why the prehistorical humans performed that type of surgery is not clear, but they surely wanted to achieve something medical! Trial and error, that’s the scientific method. I think humans have always been intrigued by the world and tried to understand it. With science, they came up a rational and careful way of doing that.