Of course we have been there with numerous *unmanned* spacecraft.
Launches to Mars:
1960s, 13 [launches]
1970s, 11
1980s, 2
1990s, 8
2000s, 8
2010s, 2
Problem is mankind can only truly discover if there. Robots are good but insufficient with the calculation compiled by a human. Lenses and robots sometimes go right by an object and that object may hold a key. Mankind is guilty of doing the same, but not to degree mankind is limited by counting on a robot to do the job, when mankind may see or sense something (if there) the human on Earth may tell the robot to miss because back here on Earth the object appears uninteresting. Too many variables relating to being there verses being here.