You're probably right.........books are always better than the film adaptations. There medium of film is rather restricting where as books can take the time to draw out a grand story with great character development.
In the film it states that Ryan was a marine for a very short time before being injured. He wasn't in combat.......he had basically gone through the marine training. This in no way makes somebody a hero. I know several current marines who have been marines for a long time that wouldn't just randomly jump in to a gunfight with several masked hooligans.....much less jump into a gunfight unarmed ala the beginning of Patriot Games. They sure as hell aren't going to be going solo into South America to rescue a few soldiers single handedly..........
Face it.........they took the character of Jack Ryan in Red October and did a complete 180 for Patriot Games and Clear and Present Danger. They brought the character back a little bit in Sum of All Fears........the Jack Ryan in the last film is most like the Jack Ryan in the first film.