why do i like indy?
Cause in the movie he's basically a normal guy, not some friggin' Superman. Movies that have decent, likable and believable characters are always better (and thanks to the tv show and various books that gave his character more depth)...I hate movies where we have protagonists who we are supposed to root for, being completely unlikeable (mostly arrogant or stupid)...
Apart from that, adventure movies always takes us to far away, unknown places; we follow 'strangers in a strange land', and these movies are interesting for showing us different (non-Western) cultures we are used to (for instance 'Seven Years in Tibet' which was light in action, but still considered an 'adventure' movie (and a very good one at that!))...
Indy may not have been the first adventure movie, but did show us how adventure, action, history and mythology could be combined very well to make a great movie.