Why didn't the disciples recognize Jesus when he appeared on the shore?
The disciples did not recognize Him because His resurrected appearance was normal and ordinary, not bizarre or visibly different. He looked like just another person, so they spoke with Him without knowing who He was until the net came full and Peter said, “It’s the Lord!”
Les explains that Jesus’ appearances after His resurrection were very normal. Mary saw Him in the semi-darkness of early dawn and thought He was a gardener because she could not define His features enough to know who He was. The disciples saw Him cooking fish on the shore and came up asking if He had any food or meat. He told them to put their net on the other side, and when the net came full, Peter said, “It’s the Lord!” If Jesus had looked bizarre, weird, and different, Peter and the ten would have understood, but they did not know who He was; He looked like just another person. Jesus also ate breakfast with them and had all the outward appearances of another human being, yet He was now immortal—able to go through walls and ceilings and be transported instantly. Les notes that we too will have new, resurrected, immortal, heavenly, eternal bodies and will not look weird, but normal like the Lord Jesus did during those 40 days from His resurrection until His ascension.