Simba was adopted from another family who had to give him up when he was about 1 1/2 years old. The poor young Mommy was getting a divorce from her husband and moving in with relatives, who had a child who was allergic to cats. Our humans still remember how she cried when she had to say goodbye to him, though she was very happy he found a new family. She named him Simba as a kitten, after Simba of the Lion King (isn't that possibly where all Simbas get their name?). So although his name is not very original, he is proud of his leonine heritage, and we feel his Manly Mane shows it was an appropriate name for him.
These are pictures from younger days: