1 human quality:
Steam locomotives require a fuel source (wood, coal or oil) and water. Humans eat and drink.
2 human quality:
Steam locomotives take time to start in the morning; they can't get up and go right away. People aren't always the best to be around in the morning either.
3 human quality:
Steam locomotives require constant maintenance to be kept in good condition. The human body is no different; stretching, working out, running, etc. are required in some degree to keep the human body fit and healthy.