The idea of a hero going home, wooing his true love, and fighting bad guys wasn't original to Scott—it's the oldest story in the world. Nor was the idea of framing the story in an historical setting—the Icelandic sagas are essentially historical novels. The blend of actual historical figures and events with legend and pure invention was unique to Scott. Some of the best parts of Ivanhoe feature the Outlaw of Sherwood and his merry men, including a particularly aggressive and hungry Friar Tuck.
By uniting myth and historic fact Scott lends context to both, building a vivid stage for his story. Today's historical novels focus on the setting itself, piling detail on detail after months of research; we get a feel of time and place, but often the narratives are less than compelling. It's not Richard the Lionheart or the futility of the Crusades Scott wants us to think about, it's something more human and universal. These elements offer credibility and realism, not the substance of the novel.
Ivanhoe is about race relations. Central is the tension between Norman and Saxon in post-conquest England, as the Saxons are oppressed by the French newcomers. This uncomfortable situation is present from the beginning, when members of both races converge at the castle of Cedric the Saxon. There's also the more remote struggle between Christian and Muslim in the Holy Land, which serves as a foil for the Norman/Saxon relationship, as all Christians were united against the heathen Arabs.
But Scott is much more bold for his time. Throughout Ivanhoe, the eponymous knight is helped and abetted by the Jew Isaac and his daughter Rebecca. In Scott's day, but even more in the Middle Ages, Jews in Europe were considered a sub-race, at the best second-class citizens filled with avarice and cunning. Scott's treatment is sympathetic, even positive, portraying Isaac and Rebecca as the most human, most caring individuals in a crowd of self-serving, vicious knights and churchmen.
There's fun stuff too, not just incisive commentary. Lots of action—meleés, jousts, fistfights, sieges, and battles. Romance, too, and sinister villains (Brian du Bois Guilbert is one bad baddie), intrigue, chases, damsels in distress, the works. Wamba, Son of Witless, Cedric's jester, is lovable and hilarious, especially his priest-impersonating exploits. And though Scott's style is dense, his prose is careful and suited to his subject. Ivanhoe is deservedly remembered as one of the great adventure novels.