Hi there.. so a normal pic on your phone is too large to upload. Some people here use photobucket.. I just take a pic on watsapp, and upload that, it seems to work.
Your girl is showing normal healthy puppy instincts about leaving home at this stage.. pups have an instinct to stay at the den until they are more physically able to look after themselves. If you think about mom leaving to go get food, and all her little ones joyously following her, there's not going to be a good survival rate.. often they are more brave if you have another dog , they imitate the other dogs confidence... cc's also love being on their own property. With a pup, it's enough to take them.a short distance from the gate, or pop them in a car and drive to a cafe that allows dogs , if she is a dog on her own I would keep the range small and tight.
Keep in mind that her just seeing people, other dogs on leads, cars, motorbikes etc is enough for socializing... she doesn't have to actually interact. Imagine if you were sitting on the floor, tied to something and these big strangers, some of them behaving very suspiciously (human stranger feels scared, pup sees that as highly suspicious) come trundling straight to you and start touching you all over. Really wierd and unacceptable in the human world, we shouldn't expect our dogs to accept that. No wonder there are a lot of dogs who actually start behaving aggressively toward people and other dogs, trying to keep them away! Cane Corso are wary of strangers as adults, she should be rewarded for ignoring strangers and dogs while out and about. Let her choose who she wants to interact with, if someone asks you if they can pat your dog, ask them to sit down, and see if she wants to touch them. She's going to feel better about strangers if shes not expecting them to make a beeline at her, staring at her and touching her. No human child likes that, no human adult likes that...
I took my guy to puppy classes, which was fun for both of us, but next time I would leave before the play time.. Puppy's don't know the rules yet, so it's the blind leading the blind.. if you have a friend or two with calm well behaved adult dogs who like puppies, make regular meeting times with them, get them to visit you, you visit them, meet at a park. In a society of dogs, the way to greet is a slow approach, in a curve, not direct, and then a hi (standing and wagging) and then a bum sniff, eye contact is diverted.. then widdling and sniffing, then maybe a game if they keen.
Please read up about fear reaction periods. It is just so important to be aware of this phenomenon. When your pup is in one, to keep within the boundaries that she is totally comfortable in. To make absolutely sure her experiences are only positive.. it's a lot to handle! In CC' s their fear reaction periods are powerful.. the reason they are such great guard dogs is they are hyper alert to possible danger, I would actually use the word jumpy... it's very important that they learn to trust you. If a strange dog is baring down, get in the way, pick her up. If a strange person is baring down, het between pup and person. In this way she will learn that she's in safe hands.
It's hard to comment on the growling thing, without seeing it. But my feeling is to lightly distract her out of it.. shes just expressing her will. Growling is actually great, it's a warning.. better than a dog who bites with no warning.
It sounds like you are doing a great job with your pup, getting her into the world in a safe way.. it is just so important. Keep up the good work. At some stage obedience training with a group using positive methods is a must. Boxergirl has a great method for at home.. one whole meal for pup is kept in a treat bag, and pup is rewarded throughout the day for positive behaviour, playing on her own, lying quietly, coming when shes called. I can guarantee you she will come 100% if you always have a treat for her. When your training becomes praise for good behavior, for behavior you want, then it just takes off.. when pup offers you behavior she knows you want. Her confidence just soars. This is what you want. Take a look at clicker training.. there's also a section on this forum for training, and a lot of discussion there. Clickers really work