Liesel is left by her mother at the Hubermanns and is also dealing with her brother's death when her story begins. I would describe her as "lonely" but she does adapt quite well by bonding with Hans, Max, and Rudy.
It would be too easy to say Rosa Hubermann is the angry character in the novel. Her tough-love attitude is based on her determination to protect her family. So, in a way, she behaves angrily but this behavior is born out of an over-protective motherly spirit. You could make the argument that Hans Jr. or the Nazis themselves are the angry presence in The Book Thief. Part of the Nazi ethos was based on eliminating people they believed were a detriment to German progress. That said, they were angry at someone other than themselves, trying to find others to blame for their problems.
Everyone in the family helps each other, but the relationship between Max and Liesel stands out in this respect. Note that Liesel reads to Max and brings him presents when he is sick.
Hans seems like the obvious choice for the wisest character. However, Liesel is a quick learner and, because of her situation, she must develop ways to cope with death, abandonment, and secrecy more than a normal child would. Death might be the wisest character. Death has a unique perspective on all of human existence. But, at the end of the novel (and the end of Liesel's life) when Death is searching for something profound to tell Liesel, he concludes "But what could I tell her about those things that she didn't already know" (550). Death goes on to say "I wanted to ask her how the same thing could be so ugly and so glorious, and its words and stories so damning and brilliant." The "same thing" Death refers to is the human race. Death wants to give her wisdom but ends up with unresolved questions he would like to ask her. So, who is more wise: Death or Liesel?