In a straight and level flight we must assume that the aircraft fuselage is trimmed so the relative airflow is parallel to the longitudinal axis for max efficiency. The wings of aircraft are usually not parallel to the a/c axis therefore they have an angle of incidence.

So therefore: An airplane flying straight and level into relative airflow parallel to the aircraft axis will have an angle of attack more than aircraft angle to the horizontal which in this case is zero... no???

if we consider the aircraft to orizontal line angle to be zero , the only way to have a lower angle is to have a negative one. no?