Why is this dog so attached??

Obviously, your uncle found Quincy in very poor circumstances. She was neglected and in abusive environment. So it seems very appropriate that she would immediately attach and bond with humans that are providing her with the basics of a home and nutrition. Whoever walks her and feeds her will probably notice the bond grows even stronger with time.

All of those activities you mentioned below (eating together, affectionate touching/rubbing, laying/resting/cuddling/sleeping together) deepens the bond between the two of you. Dogs rescued from bad situations (which includes those ending up at shelters through no fault of theirs) generally show a deep appreciation and bond tightly to those that they perceive will provide and care for them. This may be part survival instinct. Without any words spoken, dogs feel the energy and emotions of us humans (loving, happy, frustrated, sad, etc.) even in matters not directly involving them.

It sounds like you, Johnny T, gave her the affection and care that she didn't get previously. Also, since your home is new to her and she probably didn't have a good home previously, she feels that you are the one that will protect her from all the bad things she's dealt with before. I am sure, given time, she will learn that other people aren't bad either and will share the affection with them too. Please just be patient with her and help her to understand that other people in the home care about her as much as you do.