Dinah's awesome. She's wicked smart. She has a lot of common sense. She's not afraid to defend her beliefs in public.
It gets better. Some people are great talkers, some are great listeners. Dinah, however, is both. She preaches in a "clear but not loud voice" that captivates her listeners, even the ones who think Dinah's Methodism is bogus (2.35). Dinah also gives the time of day to weak, immature, very non-Dinah characters. She visits weepy old Lisbeth Bede, convinced that "the Lord has sent me to see if I can be a comfort to you" (10.20). She even takes flippant girls like Hetty and Bessy Cranage under her wing. You don't need social workers when you've got a Dinah or two around.
Actually, who needs social workers when you've got Eliot running the show? Dinah has many of the same virtues as Eliot's narrator, who tells us to cherish "all possible hopes, all possible patience" for flawed people (17.4). Dinah follows a similar philosophy of compassion. No wonder Eliot's narrator is dizzy with admiration for Dinah. But then again, who isn't?
Eliot is using Dinah to give us a new, everyday kind of heroism. Early on, we're given a glowing picture of Dinah's "generous stirring of neighborly kindness" (3.14). Wait, this is heroism? Where are the superpowers, the feats of strength, the final scene where Dinah almost dies trying to stop an alien invasion?
Well, Eliot believes that humble people like Dinah are capable of heroic acts: kindness, loyalty, and consideration. As Eliot's narrator argues, heroism can be a low-key affair. For the average reader, Dinah's traits should be more important than "the loftier sorrows of heroines in satin boots and crinoline" (3.15). And why's that? Because Dinah's heroism is a heroism that we can all put into practice. It's a realistic heroism that (if we're lucky) we see on a daily basis. Also, do any of you wear satin boots and crinoline? Didn't think so.
But this "new heroism" stuff isn't as radical as it could be. Dinah isn't rich or famous, but she is young, friendly, and immensely pretty. Eliot could have pushed the boundaries even more… but she was bound by the mores of her day. She needed to make Dinah a hot hottie in order to shoehorn her admirable, society-challenging personality traits in there as well.
She may look sweet, but Dinah has a massive stubborn streak. Or a Godly streak, depending on how you look at it. As Dinah sees it, "we can all be servants of God wherever our lot is cast, but He gives us different sorts of work" (6.27). And Dinah's sort of work involves a) ministering to the poor, b) delivering the occasional fire and brimstone sermon to easily-upset farmers, and c) denying herself a whole lot of things. God is calling her to all of this. Even the "repeatedly friend-zone Seth Bede" part.
But Dinah is capable of taking on new roles and new principles. After Adam Bede's life is turned inside-out by that whole Hetty ordeal, Dinah finds a new purpose in life. Now, the "Divine Will" is calling her to be Adam's wife. In fact, her soul is so joined to his "that it is but a divided live without you" (54.17).
Cynics might say that, in marrying Adam Dinah is simply acting on a long-running crush. But Adam Bede is a novel about adaptation and transformation. And yeah, kicking old hang-ups counts as "adaptation and transformation." Adam replaces affection for Hetty with affection for Dinah. And Dinah herself decides that "having no life of my own, no wants, no wishes for myself" isn't quite right for her (52.21).
Her values aren't flimsy. She's just discovering—like we do in real life—that first assumptions aren't always the best assumptions.