I have been a contributor to that line of thought which asserts that intelligence has declined significantly over the past six to eight generations - and I would expand that argument to include a decline in human genetic fitness in general.
But that isn't the main problem - because even if we were more able - we would merely use our greater ability in pursuit of evil.
The problem is that our society is Not Even Trying to do Good or to be Good.
Instead we have an actively evil (i.e. deliberately destructive-of-Good) leadership class that is implementing its evil policies via and upon the materialistic, hedonic, despairing, and cowardly masses - who, by their unrepented acceptance of the evil agenda, thereby themselves become evil.
When we are pointed and marching (or shambling) in exactly the wrong direction, our increasing incompetence and inefficiency at moving rapidly is not the main problem.
We need to turn around.
The core priority, without which there can be no effective change, is to turn around: to face in the correct direction.
So, what is stopping us? Simply the fact that people have no idea of what good is.
Why have they lost a sense of what good is? Simply the fact that they have rejected God, hence they have rejected even the possibility of Good...
It is not just that people don't know Good - they don't know anything - people have become mere shells of temporary notions and emotions, passively responding to changing situations.
People are utterly unfree. They could be free, with a change of mind; but people choose not to be free; because they make assumptions about ultimate reality that destroy even the possibility of freedom.
People have given-up before they have begun.
And, what is worse, modern people won't even take responsibility for having rejected God, Good or the possibility of freedom! They have chosen mental slavery and rejected the gift of Heaven - yet they will not acknowledge that they had any choice in the matter!
Thus the decline in culture, science, technology, law, education... the decline in competence, efficiency, happiness, cooperation, idealism... all these are true but merely a froth on the surface of the real problem.
We might perhaps skim-off the froth - but the river still flows in the wrong direction.