The left is too shallow since they appear to lack rational skills. Rational skills make you more independent and self reliant, whereas shallow is a prerequisite for group think. The left is driven by group think so they need to stay in the shallows, since they will drown in deep water; self floating. The Trump voter was deeper than the shallows.
Trump offer the new ideas which did not have enough time for group think, but needed common sense to be absorbed. Swimming in the deep waters allows the mud to wash off, easily. When Trump dove down into the deep water with his ideas, he came up again and again without the mud that is important to the left. If you are shallow and don't go deep; depend on fake news gossip, the mud is much harder to clean off and residue lingers. Hillary could not shake off her mud in the shallows.
Most deep people realize you can't judge a book by its cover. That is what shallow people do. The dust jacket is short and easy to read and allows one to pretend. Most of the most competent people, such as top scientists, are not pretty to look at, and may be awkward, socially. This tainted surface, relative to the left, does not mean they are not brilliant. The deep person will see this. They know the best people may not stand up to the shallow criteria.
The renewing of the mind requires we swim in the deeper waters of reason, where the majority dare not go. They stay in the shallows less the shark get them.