Im 28 and have a 1-2 cm movable lump on the edge of my right rib just under the skin not attached to the skin. cancer? and its very soft

Lipoma: It is more likely that the soft lump in your skin is a fat tumor called lipoma. However, if the area becomes sore , reddened or growing , have it evaluated.

Doesn't sound bad: It sounds like it's either a cyst (benign) or a lipoma, which is a benign fatty growth which can be soft to the touch. Both are non-worrisome . However with this said i would see a dermatologist to make sure a biopsy is not needed.