Cracks are not good. The ceiling / tile joint appears to be grout which will always crack, all changes of plane are required to be 100% silicone caulk. How was the balance of the shower constructed? Any progress pictures? Not a huge issue at the moment but very well could be indicative of movement, possible natural and possible from poor construction.

Should I worry about sealing them? found some WIP photos. Not sure if it’s helpful.

The pan is hot mop so you must be in Ca. These do not show the walls and hw that was waterproofed. Assuming they were properly and correctly waterproofed sealing the tile will not be necessary. You could technically use the shower with no tile if properly constructed and waterproofed. Tile is essentially lipstick.

Got it, @millworkman Does this help at all?

With a mud floated wall, cracks are much more serious. Mud is more stable and solid. You are getting movement from somewhere. Earthquakes, green wood shrinkng, a load bearing wall improperly removed, joists not shored up. Keep an eye on it, and watch for moisture issues.

Ugh thanks. @millworkman any additional thoughts?

Should be ok, just keep an eye on them and make sure they do not get considerable worse. Mud floated walls done properly again should be perfectly fine, while we cannot completely see yours it looks neat and well done.