Red things were probably human remains growing. maybe the MC went insane because he was alone for so long that his mind went ape-sh1t nd went insane. Mike probably died of illness and the MC didn't want to keep his dead body around so he buried it. same goes with others, after he does say the nearest hospital isn't close so who knows what happened. blue caterpillar seems to be an alien. probably got there looking for something. idk bout the floating space thing. numbers probably went backwards just for effect or the feeling or restarting the same thing over and over. most is theory besides the blue thing.