MinnFlyer, You are correct for a simple shearing action typical in building structures but by far are NOT all the loads on an aircraft wing. An aircraft wing is much more dynamic than this. Your picture does explain why they're called shear webs but in no way accuratly shows all the forces in a wing. This could go on for pages and pages to explain it but the greatest amount of shearing happens closer to the mid way between the root and tip. It happens towards the tip as well but stop increasing again as you reach the tip. NO shearing happens (if the load is "perfectly" equal on each side) at the wing root. Even if the load is not prefectly equal there will be a point close to the center where shearing does not oocure.

I know you guys are smart and I don't mean to insult anybody but I don't believe there's any way to explain this in layman's terms. Aircraft wing forces are way to dynamic.