The bad guys are another race of Toku Villains that got trapped in this new world as well.
The main villains seen appear to be notably less human than other inhabitants of the world, appear to be behind humans getting the magic seeds, and as chapter 5 reveals, they've seen and apparently fought against Rangers before.
Red used to be a shut-in Otaku without friends.
The reason Red seems so ignorant of his pseudo-flirtatious interactions with Teltina, Rosie, and Idola is that he used to be a shut in who had very few, if any, friends back in his home world, and only got friends once he joined the Kizuna Five. He emphasizes bonds and making friends so much that he's secretly terrified of losing what friends he has and doesn't want to be left alone. It's telling that the few things that have gotten through to him are either bringing up that he nearly sacrificed himself rather than see his friends hurt and that he's terrified of losing bonds.