I would say this is a beginner project that you can complete in about two hours.
Step 1: Gather your supplies
I also used some embroidery floss (but regular thread would work too) and you'll need scissors, a couple of buttons or pieces of felt for eyes & nose and a knitting needle or some other long pokey thing for stuffing the limbs. I used a sewing machine as well, but you could definitely do this by hand and it wouldn't take too outrageously long.
Step 2: Start the body
On your sewing machine (or by hand) starting at one corner of the foot, sew across the bottom of the foot and up the inside of the leg, stopping about an inch from the crotch. Repeat on the other side, leaving the crotch open.
Turn right side out.
Step 3: Cut out your other body parts
(in my picture, I've marked the heel to be cut out as the mouth, but the sock toe ended up being perfect, so I didn't need it. Your sock may vary, so as needed, cut out the heel for the mouth.)