Vertical vs Horizontal shapes printing
Thingieverse does respect the orientation an item was designed in, just like most slicers will. Designers will often choose any one of the three planes (XY, YZ, ZX) as their first by preference, then work out the other parts in relation to the first. This does often not take into account the actual print orientation it should be printed in.
In the case of this box, you'd have to turn all items around the Y-axis (the front-left to back-right one) by 90°, first to the front, then the back then to the front again, getting almost 0 overhangs.