It is too difficult to tell from photos, but it looks like you have engineered hardwood. That shouldn't matter too much. Nothing in the building industry is considered "perfectly" flat or plumb. It is quite possible there is some unevenness in the floor. To what extent, it is hard to tell without getting in a 4ft straight edge with levels.

Some houses settle over time. The newer the house, the more it will settle over time. Most of this is considered normal and acceptable. Keep an eye on it, does some measurements over the areas of concern. If you feel the floor/house is settleing "too much" then you might need to contact the builder to ensure everything is structurally sound.

By the sounds of the small amount of floor height differences, this is more into the "settling" category than it is into the structural or "bad build".