The mission plan has always involved sending a series of unmanned ships first. This is not only to deploy supplies and other necessities ahead of time, but to make sure we can actually safely land. People are kind of taking that latter part for granted because of all SpaceX has achieved, but it will itself be a historic event. We've never landed anything on Mars except tiny little rovers generally less than a ton each. And here we're talking about landing a rocket with a payload that will ideally be in the hundreds of tons, let alone the mass of the rocket itself!