Would you say there are chefs and non-chefs? Or just people who have different levels of various skills?

Musicians and non-musicians?

Ballerinas and non-ballerinas?

Of course there are. Yes where you draw the line is somewhat arbitrary and will vary from person to person but there is still a distinction to be made. You can be pedantic and say "Well everyone is a ballerina, they just might be a really unskilled one." But someone who is very unskilled really isn't a ballerina.