Just to be the nihilist in the room, I honestly think that the point of no return for humanity occurred the moment we stepped down from the trees and started to evolve. And I'm not actually kidding.
I'm not an evolutionary expert, so I'm more than likely talking out of my ass, but I was an Archaeology Major with a focus on the Bronze Age Collapse and what I can tell you is this...
From a certain perspective, the same evolutionary traits that brought our species to this point, are the very same traits that will keep us from moving forward past it. Selfishness, resource hording, greed, the urge to continually expand at the expense of others. Fear of "others" outside of ones own community; all these things in some form were beneficial to growing from hunter gatherers to urban/agricultural societies. We needed organisation to build cities, so we created monarchies. We needed ways to control the growing population, so we created a fear of a deity.
We needed a reason to not allow too many people in to our society so that we didn't waste resources, so we created borders and the concept of "others" that aren't like us. Now, all of that has to get binned if we have any hope of getting past this point because the only way forward is as single planet, not petty nation states. But every single thing that brought us to this point prevents that from happening. It's ingrained in our very DNA, so to speak.
Not having children with my (now) ex-wife. Thankfully found out her true nature before that happened. I don't know what I'd do if I had to co-parent with her and deal with her on a regular basis. So I'm thankful I could just split our shit 50/50 and then forget I ever knew her.