What I have read is that there was a rather infamous Pope (Alexander VI, who had many children by his many mistresses) whose son was also rather renowned (Cesare Borgia)... Kardashians if you will... and that the Pope commissioned a painting of Jesus and his own son was used as the model in a painting many centuries ago... and it was so popular and ubiquitous that it became THE Jesus appearance to use. He happened to have flowing hair and blue eyes, and was chosen expressly because he was more European-looking.
Makes sense to me.
However, whatever the man Jesus looked like that was just His mortal human vessel. It's what was inside that counts. After His resurrection people who knew him could have long conversations and share food with Him before realizing Who they were with. So IMHO, just as He had the evident power to manipulate "reality" to change water into wine, feed a multitude from a small basket of food, and raise the dead, He could, did, and no doubt does appear however He chooses.