Clearly, the edges of these two pieces are not going to fit together. I’ve tried pinning every which way from Sunday, and I only manage to catch every bit of fabric in the stitch. And this is just step 7 of the first project in a book’s length tutorial.
After detailed instructions (with diagrams!) on how to hand stitch a running stitch, the description for this step is simply “Sew one head piece to one body piece, matching up the raw edges . . . requires a bit of easing to fit properly (figure 4)” And figure 4 shows only the two pieces stitched successfully together.