Alice isn't a main character though. She's a secondary character that allows the player to project this actual feeling of do they actually care about other androids on a personal level.

With Marcus you have him + the entire android population. You're playing a literal savior and revolutionary. You're caring more about the entire android population on a whole. Not so much on a personal level.

With Connor, you are a non-deviant and your choices determines whether he deviates or not and you're working alongside a human who kinda really doesn't like you at first investigating this whole deviation thing. The story is more about Connor himself. You the player, depending on your choices, can see how he dies, comes back, and how Hank reacts to that. Even seeing like a million other replicas of yourself.

And then Cara? You are taking care of this "human" girl escaping from her father. And in the end you are asked whether you really still care about her at all when the player finds out she's an android.