I tried walking without shoes again, (after giving my feet a day to recover) and this time had much more success. My feet were somewhat sore still but it didn’t seem to be a topical issue so I pushed on in operation: build callouses.  After about 15 minutes the area of the balls of my feet nearest the outside of my foot started hurting so I tilted my legs in so that the opposite side would hit first and my foot would kind of roll.  That started hurting so I tried landing on my toes and then rolling back.  That started hurting so I started striking with heels again, defeating the purpose of me trying to walk barefoot in the first place.  I’ve come to a conclusion: Humans were not designed to walk on their feet.