Why was the steam engine inveted?

Why was the steam engine inveted?
The saying goes 'need is the mother of invention.' It must have been thought that the use of a machine to produce power could take the load off of manual and animal labor. Indeed the steam engine saved a lot of time and improved efficiency. The establishment of steam engine power propelled civilizations use of non-renewable energy accelerating the rate of technological progress. As rail networks spread across the world the movement of people and goods became possible on a massive and rapid scale.