In the song, the main reason Dylan uses ain't instead of isn't and instead of them is to show that he . is not part of the lower class
can use dialect
is not prejudiced
does not understand grammar

Read the following scene from trifles. sheriff (chuckling). married to the law. (moves toward the other room.) i just want you to come in here a minute, george. we ought to take a look at these windows. county attorney (scoffingly). oh, windows! sheriff. we’ll be right out, mr. hale. (hale goes outside. the sheriff follows the county attorney into the other room. then mrs. hale rises, hands tight together, looking intensely at mrs. peters, whose eyes take a slow turn, finally meeting mrs. hale’s. a moment mrs. hale holds her, then her own eyes point the way to where the box is concealed. suddenly mrs. peters throws back quilt pieces and tries to put the box in the bag she is wearing. it is too big. she opens box, starts to take the bird out, cannot touch it, goes to pieces, stands there . sound of a knob turning in the other room. mrs. hale snatches the box and puts it in the pocket of her big coat. enter county attorney and sheriff.) county attorney (facetiously). well, henry, at least we found out that she was not going to quilt it. she was going to—what is it you call it, ladies! mrs. hale (her hand against her pocket). we call it—knot it, mr. henderson. what changes might a director or screenwriter make to the original version of this scene in order to best emphasize the mood? cut dialogue from the scene to make it a more appropriate length update the setting to appeal to a more modern-day audience omit the actions of the characters to avoid confusion and chaos include the use of lighting, camera angles, and sound effects