Indeed. That's how I see people.
We all have things that we like or dislike. We all have things we consider right and wrong. We all have our goals, dreams, we all think logically about things, or get emotional about them. If you play enough with these things you can make interesting characters. At least I hope they're interesting...
Also have to be careful not to make characters declare what they like, unless they're meant to be dumb characters. You also don't have to show most of it, only the tip of the iceberg.
It doesn't have to be conscious attempt for the writer though, that's why I think most characters are realistic characters. They can be uninteresting, or a repeated cliche, sure, but they're still realistic.
As I said, unrealistic characters would be ones that break the world's norms without a reasonable explanation. I guess a marry sue character can infringe on that category as well, but I've seen some of these characters who weren't bad to read either.
Another point that can make a character unrealistic, is how much the world around him/her is about the character. If a character is written with the whole world revolving around him/her and everyone is worshiping him/her or can't stop talking about his/her deeds etc. That could be immersion breaking.
That being said, if that character played some major role in saving the world, or the character is a famous movie star, then it'd make some sense.
To sum it up, for me unrealistic character is defined by the influence they have on the world around them, if that influence is treated in a realistic way, then their personality can be anything!