We often struggle to focus and think deeply. It is not because we are not trying hard enough. It is because the limitations are built into our brains. Maybe the things we find difficult today are not really that complex. It is just that we are not naturally wired for that kind of understanding.
I’m not really sure it’s our brains that are the problem (at least most of the time). Distractions come from many sources, not least of all the many non-brain parts of our bodies.