Are gestures like exchanged glances, head-shakes, or a tenugui at the neck just to guide the audience's eyes — or do they mean more?

The question observes the function of gesture closely, and the answer is: both. Kabuki gesture is at once a sign carrying meaning and a piece of stagecraft ordering the traffic of the stage — the two layered into a single movement.

Start with meaning. Kabuki gesture has been honed into sign over four centuries of performance. A shaken head signifies denial or deliberation. The tenugui, a hand towel, is especially rich in vocabulary: held over the mouth it says shyness or reserve; pressed to the eyes, tears; wrung tight and set at the neck, resolve. The same cloth becomes a different word according to its use. Audiences were raised to read these without explanation, which is how scenes advance with no dialogue at all.

Then there is the layer of traffic. When two actors exchange a look, the audience's eye gathers naturally between them. When a head shakes, the gaze follows the motion. Several actors are always on stage, and viewers are unconsciously searching for where to look. Gesture works as a quiet signal marking the place to attend to — carrying the eye in advance to where the next event will occur. That meaning and traffic are not separated but folded into one movement is a measure of how finely kabuki is built as a theatre of style.