If he was alone it would make sence but he has a sidekick.
The Lone Ranger was named so because the character is the only survivor of a group of six Texas Rangers. Wikipedia
And his mask is cut from his brother's vest, who was one of the other six Rangers.
I didn't know that about the Lone Ranger's past, but was delighted to find out.
It would have made more sense to title it The Lone Ranger and The Lone Indian, since both of them are the last of their kind