Was the 20th century the most bloodiest century in human history?

In documented history, The 20th by far. Between 2 world wars, the spanish flu spread from the trenches around the world and doubled the WW1 deathtoll. In terms of percentage of populace the great plague 1665-6 probably took more, and combined with conquest of the Americas the 17th is a contender.

Despite the much higher post-industrial population.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.