There are few canine behaviors that elicit a stronger reaction from owners than when a dog begins humping other dogs and people.
Behavior Issue: Dog Humps for Dominance
We just rescued a Jack Russell Terrier cross from the pound, and she has taken to trying to hump me. She doesn't do it to anyone else. Is there a reason for this?
~~ Caitriona McGee
Jack Russells are feisty little creatures and they really like to be the most dominant creature in the room. Since most dogs are spayed before they leave the shelter we probably don't need to address that here. Basically, spaying reduces the hormone levels that drive this behavior.
That said, I suspect your dog is humping you because she thinks she can establish dominance over you. I believe putting the two of your through an obedience class will help you establish your proper place as your dog's leader, and nip the humping problem in the bud.
Thanks for your question, and I hope you find this suggestion helpful.