Why is right equivalent of forward, and why is forward down???

I think that the direction of 'right' is considered to be forward because of the 'number line' in math, where every number to the right of zero is a positive or 'greater' value and every number to the left is a negative or 'lesser' value. As for forward being down, i think that it has to do with a combination of clockwise motion, obsever orientation and the 'number line'. Think of a watch. Both the hands are on '12'. As the hours progress 'forward' the hands move in a clockwise rotation 'down' to the 'right', the direction of 'right' has already been established as 'forward' by the number line, and this stengthens the connection. As the hands move past the '6' they, according to the observer position, are now moving in an 'upward' 'left' motion. The clockwise corrolation of 'right, down, forward' is broken with this motion, however the connection between the direction of clockwise = right = positive numbers = progress, is too strong, so the mind continues this association. I think that the 'right = forward' is much stronger than the 'forward = down', however, both are related.