Some dogs just don't play with toys. Annie may never had toys to play with, or she may never had the desire to play with toys.
My first dog, a spaniel/retriever mix, never played with toys. He would fetch for hours, and loved to chew on sticks and rawhides, but never played with toys on his own. My present dog loves to play, which surprises me as I think she was tied and neglected for the major part of her first year of life. Often, dogs who did not have an opportunity to develop normal play behaviour at an early age never get into toys.
At Annie's age, I don't think she will change and become toy driven, but it won't hurt any to keep trying and encourage her. She may be more prey driven. If you have a ball or a Kong on a rope and wriggle it around on the ground and run around with it, does she show interest? Would she play tug? An excellent game to build their interest in playing with you.
You can also try those treat balls, where you put a treat into it and she has to work at getting it out. Might get her started into interacting with objects. If she is food driven, you could use small bits or food rewards to get her active. If you can get her running to you from across the yard for a bit of a food reward, you can build on that to encourage other activities that will get her moving.
Also, you have only had her for a week. She might take a couple of months to settle into your family and relax enough to show her true personality. At this stage, she is still adjusting and trying to process all the changes in her life, so give her time.
Thank you so much for rescuing! Annie is blessed to have a caring person like yourself in her life. Lots of walks and fun, rewarding activities will go a long way into into getting her back into shape. Once she is slimmed down and active, she may start showing more interestest in toys, but if not, that is just who she is.