I have noticed that every person who achieves any kind of fame in the entertainment industry is distinctive in some way.
Think about any successful actor, and you’ll realize that there is something, and often more than one something, about them that is unique to them. It seems that the more successful they are, the more likely it will be that their voice is one of those things. You can recognize them in an animated production after they’ve said three words.
This also carries over into the music industry, but with an additional caveat. The artists that last for years on end and album after album are always the ones that write, sing, and play their own material. Artists that specialize in singing what others write for them will be gone after one or two albums.
You may be able to find a few exceptions, but I think these are good general rules.