Does homeowners insurance under structural cover cracks in the wall and house coming away from the slab?

Not if the slab is cracking due to normal settlement. Many homes have cracks that form during the first 10 years after they are built. Why? there was no weight bearing on the soil where the structure was built. Now there is a lot of weight. Soil is stronger in some areas (rocks) and weaker in others (sand and swamps). A house is built on a large area so the soil may be soft in one area and strong in another. Engineers call this differential settlement. One part of the house settles or sinks into the ground faster or slower than another area.

Good buildings have cracks. After about year 10 the cracks should be normalized and then you fix them and move on. Now if the cracks are opening or widening then you have a problem that you need to find. If the cracks opened up a little after the house was built and have not moved in several years then fix the cracks and move on. Again if cracks are getting larger then you need to seek the reason for the cracks getting bigger. The reason is usually water. Soft dirt is mud which don't hold up much weight. Check downspouts and if you have flooding when it rains hard.

If you have normal settlement associated with a new home cracking and poor water management this is not a covered insurance claim.