It is really important to socialize your dog and get it used to other people and animals at a young age and if you rescued this puppy at five months then maybe the previous owners didn't do this. It is not good that your puppy is already showing signs of aggression at such a young age

Your puppy could also be getting used to you and its new home; it could still be scared and unsure. If its experiences with people haven't been good and it wasn't treated very nice by the previous owners then your puppy could be showing aggression to you for that reason also.
It is important to show your puppy that you are good and people are good and they won't hurt you. Give it lots of praise/treats for being good and not being aggressive around people. If your puppy starts growling at you tell her in a loud firm voice NO so she knows that was bad and then when she stops lavishly praise her. If she continues to growl put her on a time out in a 'naughty place'; a bathroom, laundry room, her crate, ect untill she calms down the praise for being good.
If she barks at people when they come to the house tell her again NO. When she has stopped and is calm praise her with attention or treats and the person who entered should do the same also to show her people coming in the house is good; they can give her treats too for being good when they entre.
Another thing to socialize is take her to a doggy day care, obedience training, dog park...really anyplace social where they can interact with lots people and animals to get used to them and see they are good
I hope that helps!