Creation

God: And now, on the seventh day, I finally rest. Seriously that was a lot of work, but I have to say I'm feeling pretty good about it.
Biblical Debbie Downer: Yeah its alright, kind of a shame that you are probably just gonna wash it all away after you realize mankind isn't as virtuous as you had hoped, almost seems like a huge waste of time.

Early Man

Caveman: Ah! I have finally invented wheel. Make everything easier, change world.
Prehistoric Debbie Downer: Too bad your wife left you while you spent endless months perfecting it, huh? It also doesn't help with the constant threat of wild beats and our painfully short life span.

Renaissance

Michelangelo: Viola! The Sistine Chapel, she is finished. Years of work and precise details are finally realized!
Euro Debbie Downer: Hey way to go! Definitely must have been difficult on your body to inhale all those fumes upside down and constantly get paint dripped in your eyes. Also this "masterpiece" will eventually begin to deteriorate, forcing museum restoration technicians to continually update it, destroying its essence. Plus, you missed a spot.

Destruction of the Berlin Wall

German Guy: Zis is a great day to be alive! Goodbye Iron Curtain, vee are now vun country!
Easter German Debbie Downer: Who the hell is going to clean all this up?

Women's Suffrage

Susan B. Anthony: We are equals! Hence, every discrimination against women in the constitutions and laws of the several states is today null and void, and men will respect that!
Flapper Debbie Downer: HAHAHAHA, oh my god… you are serious. Awkward. Does one vote even matter that much?

Global Warming

Al Gore: Ladies and gentlemen, the warnings about global warming have been extremely clear for a long time. We are facing a global climate crisis. It is deepening. We are entering a period of consequences. Churchill also said this, and he directed it at the people of his country who were looking for any way to avoid having to really confront the threat that he was warning of and asking them to prepare for. He said that he understood why there was a natural desire to deny the reality of the situation and to search for vain hope that it wasn't really as serious as some claimed it was. He said they should know the truth. And after the appeasement by Neville Chamberlain, he sad, "This is only the beginning of the reckoning. This only the first sip, the first foretaste, of a bitter cup which will be proffered to us year by year – unless by a supreme recovery of moral health and martial vigor, we rise again and take our stand for freedom."
Modern Debbie Downer: I totally agree.