When your puppy played with her siblings and her mama, she used her mouth. When she plays with you, she'll probably want to use her mouth until you teach her not to. Most puppies don't mean to hurt you, but those puppy teeth are very sharp and you don't have fur to protect your skin like her canine playmates had. Your puppy is motivated to mouth and bite not because she wants to hurt you, but because she thinks it will get you to play—after all, it works with other dogs! I'll suggest two effective ways to teach your puppy not to mouth and bite.
First, use the same method we just discussed to stop jumping up. If your puppy nips you, say “Ouch!” and then stand up and ignore her. If she jumps up, keep ignoring her—you can teach her not to bite and not to jump at the same time! If she bites your ankles or pulls on your pants, leave the room, ignore her until she calms down, then come back, sit down with her, play gently, and try the second method.
Second, give your puppy something else to put in her mouth besides your hand. When you pet her or play with her and she takes your hand in her mouth, gently offer her a chew toy and continue to pet her. She'll learn that hands are not for chewing, but they're great for ear scratches and belly rubs. If she insists on mouthing and biting you instead of the toy, go back to method number one.
A word about tired puppies: Puppies are like young children. Sometimes they get so tired that they're completely out of control. They're not smart enough to just go to bed, so they keep playing and getting sillier and sillier from fatigue. If your puppy has been out playing for a while and is getting more and more out of control, put her in her crate, give her a treat, and let her rest. Very often a tired puppy will protest for, oh, two minutes and then fall fast asleep.
If you're having a problem with mouthing and nipping, make sure that no one plays tug-of-war or other rough games with your pup. The last thing you want to do is encourage your puppy to grab for things or compete with people for possession of things. Teach her instead to give you toys, which you can then throw for her to retrieve. The no-roughhousing rule applies especially to children.
Interaction between children and puppies should always be supervised by a responsible adult who is close enough to intervene immediately if play gets out of hand. Don't expect a child younger than 12 or 13 to be able to apply any of the training methods I've outlined. An adult needs to be in a position to help. Children tend to react to nips by screeching, pushing the puppy away, and generally acting excited. Your puppy will think the child is playing and will probably keep jumping and nipping. The child will get more excited, things will quickly get out of hand, and someone could end up injured, frightened, or both.