A couple of thousand years ago, humans built massive engineering projects, including the Pyramids, massive irrigation and earthwork systems, and tunnels, and bridges, domesticated wild animals, produced metals - including steel - out nothing but wood, water, and low grade ore, etc, etc.

They did not have internal combustion engines, or electricity, or the ability to machine parts to high tolerances, but ancient engineers cared deeply about efficiently transforming mechanical energy from one form to another.