Kale, Broccoli, Brussel Sprouts, Cauliflower, Kohlrabi, and Cabbage are all the same species of plant - Brassica Oleracea.
We did something similar to dogs. We selected for the traits we wanted and the organism changed over time.
We picked out a waterproof coat for the Labrador, we selected the juicy leaves of Brassica Oleracea to make Kale.
Just like we enjoyed the lovability of the Golden Retriever, we adored the flowers which became Broccoli.
We wanted Big Dogs, so we made Great Danes. We wanted robust Lateral Buds, so we made Brussel Sprouts.
We needed Huskies to pull sleds and we needed Flower Clusters to make Cauliflower.
We made some strange stuff too. The Bergamasco Shepherd looks a mop for the same reason that Stems elongated to make Kohlrabi.
If we went back in time 5,000 years, we would see a human with two companions - a hound and a cabbage.