They've gone back and forth on comic relief over the years - it wasn't just Orks. In the Rogue Trader days there was a lot of nonsense on a lot of sides.The orks are an obvious comic relief
Although even they have the interesting element of being able to make things work by simply believing they do.
But Orks were seen as the most crude, and GW leaned into this over the years. In a way, just like in fantasy, you see the overlay of human stereotypes onto each respective faction. There's a reason (Fantasy, not 40k) Orks were the poster faction for Blood Bowl, which is "what if Warhammer did American football".