Zira is coming straight from Disney Canon and to some degree its crossovers too, since they're canon as well. Essentially this is the very literal canon incarnation of Zira. Because the second film is a direct follow up of the first, everything that happened in The Lion King is also considered canon here. Zira is literally a talking lion, and like in most cartoons, talking ability in animals represents the degree of sentience the character has. In the films, there are a lot of wild animals from a bunch of species that make normal animal noises, but only a handful of those have the ability to talk / talk back to speaking characters. An example: Scar [another talking lion] catches a mouse and plays with it, all the while taunting it and making it obvious that he intends to eat the small animal. Scar is obviously talking, but the mouse is only capable of normal mouse-like squeaks and shows no capabilities of non-verbal response.
Now here's the thing; Zira is very much a lion living in the African savanna. But at the same time, she's also been equipped with some super-human [no, pardon me: super- lion] powers. She's designed in such a way that emulates and personifies people; from referencing human tools and human history, to using portions of her body like how they would function if they were human limbs. Her front paw/finger joints are opposable; she uses them like fingers in the film, and they're capable of moving independently. She also sometimes stands on her hind legs and maneuverings her front legs like arms, waving them around or grasping things like they're hands since her paws are capable of making fists.
The thing with cartoon Disney canon, is that often characters are thrown together in spin-off crossovers like the TV series House of Mouse – where Mickey Mouse runs a dinner + theatre sort of gig, and lots of characters from different movies all get together as his guests. Lion King characters are not exempt from this show, and a bunch of lions [as well as other animals] are seen sitting at tables, conversing with other human / non-human guests, and eating food served on plates from characters like Chip and Dale or Donald Duck. Scar once showed up with his hyena posse in tow, and they all played nice with some other Disney baddies like Hades from Hercules. Where I'm going with this is that Zira – who's already far too human for a lion – would not take it too badly to find herself in a mostly human world. It also wouldn't be amazingly out of place for her to see other non-humans / Non-animal people walking around because Scar dosen't have a big problem hanging with Ursula the ladypus.
But on to more ways that Zira isn't quite liony enough. When she speaks [or sings] she says things like “[I love them] drums of war,” or “and then my flag will fly,” for instance. Now aside from the fact that lions don't usually sing nor talk, they don't usually properly reference nor understand human tools either. Zira obviously does. Not only that, but what is one of the things that separates man from beast? If you said 'the ability to wield fire,' you'd be only half right, because guess what lioness concocted a plan that involved setting the savanna on fire in order to set in motion a dastardly plan of revenge? If you said 'Zira,' you wouldn't be wrong. The interesting thing here though, is that the other African animals didn't take to well to their grassland home burning up, and react in much the same way you'd expect any wild animals to. Zira, and her followers though; not so much; they wield fire pretty expertly for animals carrying around flaming branches in their mouths.
Let's look at some more weirdly far fetched examples that are actually canon shall we? Okay. So way back in the first movie, a meerkat and boar character say to a lion protagonist, “What do you want me to do? Dress a drag a do the hula?” Do you know what happens next? The animals put on costumes made of grass and plants, and then do the hula. “But wait,” you might say, “it's all well and good that the traditional Hawaiian garb is made of natural found objects, but ain't it a tad weird that these animals have a concept of this type of human culture... as well as n idea of what is cross dressing? ” My answer to you: yes, but that doesn't stop them because they're pretty much people.
And that's what Zira is mostly. She's not so much a lion, as a person shaped like a big cat who prefers to eat her meat raw... and alive. Don't forget though, that's she's still equipped for running around the Savanna shaped like a lioness. In fact, she's almost TOO equipped. She's capable of some pretty intense feats of acrobatics and strength that no IRL lion would normally do, and she's kind of crazy strong (all things considered); she sharpens her nails on rocks man. What animal does that? Also, her irises are red, and her sclera gold. That shit ain't normal bro. Oh well, this is Disney we're talking about. It's all cool.
As for her situational history:
She is the widow lion of Scar, the big bad lion from the first film. Because she's still loyal to the bad guy, her and her pride of lionesses that refused to follow Simba [Protagonist lion that defeated Scar] have been exiled to the Outlands. The Outlands are a barren desertlike portion of the savanna and it's tough living. There's not much food or water out there, but a lot of enormous termite mounds. Somehow though, Zira manages to survive and so does her little pride; they even live inside a preposterously big termite mountain. And even though there are two males in this group, Zira is still the alpha queen.
Okay, so this living arrangement kind of sucks and everyone in exile hates it, and Zira has been plotting and working toward a huge climax revenge where she wants to SLAUGHTER ALL THE OTHER LIONS [that are on the protagonist's side.] She's also got a special little hatred for Simba since this is all his fault and he killed her husband. There's one thing stopping her from just trouncing on up to the other lion pride and killing everyone herself though, and this is the fact that exiled lions aren't allowed in good-guy-lion territory lest they face the consequence of death. All the other African animals are cool on this and would report the bad lions in immediately too.
Anyway, Zira trains her kids – adopted and otherwise- to play through a complicated double agent role to win Simba's trust and then stab him in the back. Meanwhile her lion pride gets ready for a big lion war once Simba's dead. Long story short; the double agent lion is wooed over to the good side via the power of true love and Zira has to start her war while Simba is still alive. Later her own lion pride is wooed to the good side too, and Zira eventually falls off a cliff into a flash flood going the way of most Disney villains. She has a moment of obvious terror when she's falling off that cliff, but once offered help by a good guy, she decides suicide would be cooler and does that instead.
Zira is a sadistic, bloodlusty lion, who is hateful, obsessive, manipulative, violent, power hungry, unhinged and unable to change. She's been obsessed with revenge ever since Scar died, and instead of look for a better life for her, her children and her pride, she dedicates all of her time to plotting Simba's death [and the death of all the other good guy lions]. She ignores the well being of her children and comrades more than once, and this eventually forces her biological son into a situation where he gets himself killed. Instead of realizing her role in that, she instead blames another lion, and that's how things usually go. Zira is completely incapable of seeing her fault in anything, and will always find blame on other lions. She's also obviously unhinged, and in a deleted film scene, is shown talking to her dead husband and narrating her actions [to the confusion of her kids.]
Zira is incredibly manipulative too; brainwashing her entire pride and all her children into following her goals without giving thought to what might be a safer, saner alternative. Plus she lies quite a bit and has no qualms in playing the victim, playing favourites amongst her children, or pretending to play nice with lions she hates in order to get what she wants. Because of her disposition and mentality, she is constantly striving for greater power, and vehemently hates those higher up in the hierarchy.
As an alpha lion she is also highly territorial, aggressive and combative. This comes half from her poor quality of living and half from her personality. She admits that she likes to: fight, maim, kill, hear lions scream in despair and pain, and that while she “knows it might be petty, but she hates to let [anyone] live.”
She's a lion with sharp teeth, sharp claws, and the ability to strive and lead a pride in a wasteland, so she's pretty tough emotionally and physically.
She's adept at killing and really enjoys it.
She's very manipulative and good at that too.
She doesn't have much emotional baggage tied to her children, often abusing them, offering them up to be killed, or otherwise mistreating them. Since she's a lion, and lions are known to cannibalize on their cubs [in certain situations] this isn't so bad. Except until you remember that she's more a person than a lion and that's kind of awful.
Anyway, Zira's not a picky eater. She will eat people, children of people, other animals and now that she doesn't have to scavenge for dead things, she'd prefer her prey be alive as it goes down.
She's a lion. She can't read, write, cook, or drive.
She's also crazy, power hungry, unable to see past her revenge, unable to change and did I mention crazy?
Oh, and she's evil; karma tends to screw over people like that.