People will still refer to redheads as "ginger" but only some of the time

That's a fairly new thing. Growing up, I never heard anyone use "ginger" in that way. It was always "redhead." Or sometimes "strawberry blonde" for lighter shades.

Millennial checking in, ginger was used all the time when I was a kid

Only a ginger should call another person ginger.

https://www.youtube.com/watch?v=KVN_0qvuhhw