The Klingons first appeared in the original Star Trek in 1967, in the first season episode Errand of Mercy, and were portrayed as humans with dark make-up. They appeared in six further episodes of Star Trek in a similar vein.
The Klingons as they appeared in the original Star Trek episode Day of the Dove (1968).
The Klingons as they appeared in Star Trek: The Motion Picture (1979). With minor refinements, this look would remain constant until the end of Star Trek: Enterprise in 2005.
The Klingons in Star Trek: Into Darkness (2013).
If they are Klingons, it is a baffling choice to redesign them. Much has been made of the fact that Star Trek: Discovery is set in the original or "Prime" timeline, ten years or so before the events of The Original Series. Using either of the first two designs would make sense (CBS do not have the rights to any designs from the Abramsverse movies, so would not be able to use the Into Darkness appearance), but redesigning them so they don't look like Klingons any more is both unnecessary and does little but alienate a fanbase already sceptical of the new show's poor design sensibilities and status as yet another redundant prequel.
Hopefully the producers will confirm what's going on soon.