Clarke emerges from bunker 42 days after Priamfaya. When she comes upon the Shadow Valley Clan village, the people there do not show 42 days of decomposition. Since people were dying from the radiation before the death wave hit, they would have already been dead by the time it arrived.
When Clarke first enters the village's temple with all the dead bodies, there's a man wearing a green shirt on the right-hand side of the room who moves his head from leaning forward to leaning backward.
Ancient humans built a bunker that remained fully operational even after 100 years of no maintenance, yet they overlooked the simple glaring fact that the bunker is too near to the 50 story headquarters of the commander, and in case of any catastrophe, it was quite likely that the tall structure would wall right on the bunker and it could have crushed the bunker, and if not, it would have become impossible to remove so much rubble to open the gate of the bunker. In any case, as all surviving humans were inside the bunker and all person out of the bunker were dead, who would remove the rubble in the first place from out side so as to open the bunker. So, the bunker population was bound to perish inside the bunker itself because the door couldn't be opened.
When Clarke was going to Polis, there are at least two wooden structures or boats shown. As Praimfaya was depicted as a wave of fire, it would have burnt those wooden structures to ashes.
Not knowing the background of the landing ship, it is still unthinkable that they would summarily kill or shoot at the first and only kid on an otherwise scorched planet. it is also unthinkable that Clarke would summarily shoot to kill the person even after Madi confirmed that that person has helped her so he could be good. Seems humanity didn't survived the Praimfaya, these are all just two legged creatures out to kill one another.