The idea for using steam to create motion of some kind existed since the ancient Greeks: https://en.wikipedia.org/wiki/Aeolipile https://en.wikipedia.org/wiki/A

The idea for using steam to create motion of some kind existed since the ancient Greeks: https://en.wikipedia.org/wiki/Aeolipile https://en.wikipedia.org/wiki/Aeolipile But you're right, to make it practically useful required better materials.