Character Analysis
If you think about it, the people Ed helps—everyone from the sweeties like Milla, Sophie, and Bernie Price, to the more complicated folks like the woman on Edgar Street and the Rose brothers—are all very two-dimensional. What do we mean by that? We mean they're all flat, like a piece of paper.
Because for as much time as Ed spends reading Wuthering Heights to Milla or organizing a barbecue with free beer for Father O'Reilly, we never really get to know these characters aside from Ed's very limited interactions with them. We only see them from Ed's perspective, and even then we only get a couple comments here and there from them that never really amount to anything substantive.
Here's what you need to know about these peeps: they don't really matter individually. Sure it's sweet that Ed buys Angela an ice cream when she's feeling run down, or that he gets new sparkling Christmas lights for Lua and his kids, but the actually important thing is that Ed's doing it at all. The people are just random figures that are used to help us get to know Ed, and help him get to know himself.
What do they all have in common? They're all rejects or lonely people that no one else seems to notice or care about. Ed can't understand how a woman can get raped regularly and no one stops her attacker; he thinks:
Why can't the world hear? I ask myself. Within a few moments I ask it many times. Because it doesn't care, I finally answer, and I know I'm right. It's like I've been chosen. But chosen for what? I ask. The answer's quite simple: To care. (1.6.33)
Yikes. It's a gruesome way to make a point, though also pretty effective.
In some ways Ed is the perfect guy to care about these people because he knows what it's like for no one to care about you. Think about it—he's got his dog and his cab… and that's about it. Until the end, anyway.