Yes, there existed what might be called science-fiction art before Frank R. Paul (1884-1963) appeared on the pulp magazine scene, but many believe Paul is the guy who counts as the effective inventor of the genre. And that "many" includes illustrator Frank Wu who posted this strong endorsement of Paul that includes a gallery of his magazine covers. So if the examples shown below aren't enough Paul, be sure to explore the link to Wu.
Paul was born in Vienna, trained as an architect, studied in Paris and migrated to the United States before the Great War. He came to the attention of Hugo Gernsback, who published science-hobbyist magazines. Science-related fiction was part of the content, and by the 1920s Gernsback had spun off a new magazine -- Amazing Stories -- that dealt with what we now call science-fiction. Frank Paul did the cover art.
Paul's strength was his imagination. He conjured up space ships, space suits, flying saucers and other items central to visualizing ultra-high-tech futures.
Paul's weakness, in my opinion, was that he was at best a journeyman artist. His magazine cover paintings strike me as being little more than elaborated cartoons. While I'm happy to give him his proper due as a pioneer, I also cannot deny that I almost wince whenever I see almost any example of his work.
Here are a few of Paul's magazine covers. As usual, try clicking on the images for larger, crisper views.