I feel like Thirteen is already a better person than some of her previous regenerations and she’s still learning who she is.
What I mean by “better person” should probably be explained. The doctor can customarily save the world two times over and he’s succeeded in his mission but then he doesn’t see the fault in treating his companion unfairly, consciously or unconsciously throwing them into danger, or not being concerned with their lives.
Thirteen is… a little different. From the beginning, she displayed so much kindness and empathy towards her companions. She went to Grace’s funeral, watched Ryan go up to the hill to ride his bike, asked about their lives and cared about their respective situations.
— maybe he doesn’t always mean to, but the Doctor could be rather careless about his companions lives and almost immediately wants to invite them to run away with him. Thirteen didn’t. She stayed. She cared. She listened.
In Rosa, she understood that this wasn’t a safe environment for Yaz and Ryan, and told them to sit it out, but they stayed because they wanted to. She asks if they’re okay and tells them to be careful.
— not the Doctor inadvertently coaxing them into a risky situation with little to no concern or like Ten not really being understanding of Martha’s concern about her race in the era they were in.
Even in this preview clip from the next episode, Thirteen keeps her promise to bring them home and literally doesn’t ask them to stay, even though she has clearly become attached to them and wants them to, and is so excited when Yaz invites her in for tea.
And this doesn’t take away from anything else. Thirteen is just as fierce and effective as the other doctors where it concerns saving the world and protecting people, but she’s just a lot nicer and more caring when it’s necessary to be.
(P.S. I don’t mean all of the previous regenerations are guilty of the faults I detail above, just some of them.)