Harrison Ford is so bad in the first Star Wars (Episode IV: A New Hope) that in 1977 I'm sure most people were positive his career was over.
But Lucas/Spielberg saved him with Raiders.
I disagree that Lucas saved him with Raiders. I think a lot of people wanted to see Raiders because that Han Solo guy was in it. And both the film and Indiana Jones were awesome. And...Harrison Ford was Indiana Jones.
While you may be right about Ford's acting in the first Star Wars, you lack perspective. The thing that was cool about Star Wars was that no one had done anything like it before. Science fiction wasn't well represented in films, with the only exception maybe being 2001. But look what Lucas started!
Since the first Star Wars, there have been some very high quality science fiction films, including one that Harrison Ford did act well in. And that's the trouble with most of the Star Wars films. After setting the standard for the rest to follow and having a long absence to come up with some decent stories (there have been some good Star Wars books written since the first trilogy), Lucas gives us Jar Jar Binks.