The wolves are actually werewolves or some other kind of fantastic wolf-like creatures who can assume human shape (or who look as humans by default and can turn into wolves)
Them looking exactly like humans isn’t just Serendipity Writes the Plot. They are able to convincingly pass as humans in broad daylight (the wolf in the original fairytale at least has the advantage of lying in a dark hut and covering himself with blankets). When Red Riding Hood rescues the Wolf-Cub, who isn’t even attempting to disguise himself, she doesn’t realise he is, well, a wolf-cub. Even if we assume Red Riding Hood has an extreme case of facial blindness, other people don’t recognise the wolves as wolves either: for example, when they rob the two Catholic priests, the priests cry "My children!" after them, showing they clearly perceive them as humans. Moreover, there are actual animals shown in the film (a pig, a dog, a herd of cows), while in other films of Nechayev's there are costumed actors or puppets even in place of background animal characters. And in addition, the hunter’s dog reacts to the Wolf-Cub as a recently-abandoned good-tempered dog would react to a kind human being, rather than getting suspicious over the approach of a canine stranger. The She-Wolf has a bad wound (caused by humans) that has rendered her incapable to hunt
Despite her wild hatred of humans, she never thinks of getting her revenge herself. Even if she’s elderly, it would hardly be difficult to attack a ten-year-old girl… Unless, that is, the She-Wolf can’t attack. She also stays in her lair throughout the movie, not even going to search for her grandson after he runs away (and it’s implied she cares for him, despite his non-I'm a Humanitarian fondness for people). It’s quite probable, therefore, that she has been wounded by a shot or a trap and can’t even walk any distances longer than from one wall of her lair to another. Of course, it only amplifies her loathing of everyone and everything human (it’s Truth in Television that one of the main causes, if not the main, of man-eating tendencies in animals is getting badly wounded, quite often by a gun; many among the most vicious man-eaters were created this way).