The ancient Titans of myth were real, and their imprisonment in the cells of Tartarus ironically saved them from the global flood that wiped out the Olympians who defeated them. Now in the modern day, melting polar ice is slowly cracking open the entrance to their prison in what is now called Antarctica, and the Titans have emerged to reclaim rulership of a world that has forgotten the terror of being beneath the feet of giants the size of mountains. Opposing them are the armies of the modern-day world, who will run out of ammunition before depleting the Titans' numbers enough to defeat them, and a nascent population of superhumans created using genes spliced from an Olympian body found buried in the Siberian ice.
The Titans vary in size (and their size is often variable even for an individual), from being only three meters tall at their smallest, to the 300-500 meter juggernauts capable of leveling cities with enough effort, to Kronos himself, towering at over a mile in height. Some of them are capable of flight, and in their efforts to subdue humanity, will make no effort to mitigate the damage of their passing.
So, the question is: If a flying Titan of say, 300 meters in height, with a similar proportional body profile as a human, flies in an upright position (standing upright, rather than a Superman pose) at about the same speed as a commercial jet, Mach 0.8-0.9 or so, a hundred meters or so above the ground, how much damage would you expect to occur from the displaced air? Would it be devastating or a nuisance? How do the figures change if 1.6 km-tall Kronos attempted the same feat? What if they were supersonic, flying at Mach 1.5 or so? There is no apparent exhaust being used to propel them, so we're only dealing with the displaced air.
EDIT: I've been advised to narrow the focus of the question, so let's just go with with the question of a 300-meter Titan flying at Mach 0.8 about a hundred meters above the ground.