Doesn't a character need to be relatable and unique?
Jim S. asked: I agree it's important to make a compelling character. But a unique character that the audience cannot in some what relate to, might not be very interesting. Doesn't a character need to be relatable and unique? We relate to Aunt Jane because we all have a grandmother like her. But we are interested because she is, at the same time, different from our grandmother. She makes footballs. But if the audience could not relate to her, if she were from outer space, the fact that she made footballs would not be as interesting. Doesn't a good character need elements of both the familiar and the unfamiliar?
You're on the right track in thinking that a character needs to be someone that we can relate to. We connect most with stories that are relevant to us. However, I would say here that that's why we lead with People. And because of our shared, human experience, we do relate to people in some way or another.
Think of Walter White in Breaking Bad. Even though his Uniqueness as a teacher-turned-meth-producer-and-dealer is probably unrelatable to most of us (I hope!), we can still relate to other aspects of his very human struggle to secure his family financially before he dies. Or think about Lek in The Elephant Whisperer (if you haven't seen it yet, I'm linking it for you here.) Her Uniqueness having grown up with elephants as "sisters," is completely un-relatable to me, as I'm sure it is for most of us. But we still relate to other parts of her character and her also very human journey to love animals and heal through kindness. It's because she's a person, and we naturally connect and relate to other people. You'll also notice that both of these character's have strong Desires, and its that Desire that really cements that connection.
I'd also say that how we relate really varies so much depending on the person watching. How I relate to Aunt Jane may be completely different than how you relate to Aunt Jane. But the common denominator is that she's a human being, and we both relate to her in some way because of that.
Finally, I'd like to highlight your note that we relate to Aunt Jane because we all have a grandmother like her, but we're interested because she is, at the same time, different from our grandmother. Bam! You really hit it on the nose here. This is exactly the difference Uniqueness makes and the role it plays as a strong character's Big 3 Things. Uniqueness is simply what makes this person different enough to catch our interest. There has to be something that provokes our curiosity so that we're drawn in and can fall in love, and relate to, the character from there.