How does the aircraft keeps propelling forward when airflow and thrust are not aligned? Assume an aircraft is flying at an angle of attack of 10 degrees, and that the incidence angle between the aircraft fuselage and the wing as well as the angle between the wing and the engine mount is also 0 degrees, the thrust force is at 10 degrees relative to the incoming velocity. My question is, since there exists an angle between the incoming the airflow and the thrust force, how does the aircraft keeps propelling forward straight?
I mean if I break down the thrust force into its components, then one component can be added in the direction of lift, and other component can be used to counteract the drag. But why would this make the aircraft to keep moving in a straight path? Because aircraft itself doesn't know how the component breakdown should be established, and also it just sees a resultant thrust force. Moreover, theoretically, I can make the component breakdown of the Thrust force using a different co-ordinate system, but still why would the aircraft keep on propelling in the same straight direction?
Let us assume level flight. Then the forces acting on the aircraft are shown in the following sketch (not necessarily to scale):

The forces are :

the total aerodynamic force $ F_A $, which is split into two components: lift $L$ (perpendicular to direction of motion) and drag $D$ (parallel to direction of motion)
the weight $W$
the thrust $T$, here acting slightly upwards because of the angle of attack $\alpha$

For un-accelerated level flight, the sum of all forces must be zero. This is independent of the coordinate system you use to split the forces. In our example, this is given by these equations:
$$ L + T \sin \alpha = W $$
$$ T \cos \alpha = D $$
At a given angle of attack, these equations will only be true at one particular airspeed. At higher airspeed, the lift would increase resulting in a climb, which then changes the angle of attack. At lower airspeed, the lift would decrease resulting in a descent.