In bowl, combine flour, ginger, cinnamon, baking soda, salt, and allspice. In large bowl, with mixer on medium, beat butter and sugar until fluffy, about 3 minutes. Add molasses and egg, beating well. Reduce mixer to low; beat in flour mixture until combined.
Divide dough in half. Shape each half into disk. Cover in plastic wrap, and refrigerate 1 hour.
Roll out dough to 1/4-inch thickness between two sheets of wax paper. Remove top sheet of wax paper; invert dough onto baking sheet; remove wax paper.
Heat oven to 350°F. Using cookie cutters, cut out shapes of boys and girls. To make boys leaping, carefully bend one knee, making sure not to crack the dough. Gently shape one arm of each girl straight out. Using cookie cutter, cut two additional arms per girl, and attach at bottom of skirt for legs.
Bake 12 minutes. Cool completely.
To decorate, thin icing with 2 tablespoons water. Divide royal icing into 4 small bowls. Tint one bowl blue, one green, and one red with food coloring. Leave one white. Decorate gingerbread cookies as desired.
In large bowl, with electric mixer on low, beat together powdered sugar, powdered egg whites, water, and cream of tartar until well combined. Increase speed to high, and continue beating until stiff peaks form. If not using immediately, press piece of plastic wrap directly onto surface of icing and store in refrigerator for up to 1 week. Bring icing to room temperature before using.