I read in my physics textbook that fluids flow from regions with higher mechanical energy to regions with lower mechanical energy (1).

Also, the Bernoulli's equation states that:
$$
PV + mgz + \frac{1}{2} mv^2 =constant
$$

I find these two statements contradictory. If the total mechanical energy at any point in a fluid body is constant, as according to Bernoulli's equation, then there would be no flow in a fluid body at anytime. In other words, the statement (1) doesn't even apply in the first place because there is no variability in the mechanical energy in a fluid body, as according to Bernoulli's equation.

I know that I am missing something and appreciate any explanation.

[![enter image description here](https://i.stack.imgur.com/biRrB.jpg)](https://i.stack.imgur.com/biRrB.jpg)

[![enter image description here](https://i.stack.imgur.com/HySbF.jpg)](https://i.stack.imgur.com/HySbF.jpg)