It all depends how you want to define "flight"!
Lighter than air
Heavier than air
Glider or powered
Control by body weight/position
Control by mechanical means
How many/what type of Controls are required to define it as an "Aeroplane/Airplane"?
What is defined as "Controlled" i.e. does a fugoid wave and crash landing count?
What is the exact definition of "Sustained"?
Then you get on to matters which are harder to verify in retrospect, like "Assistance":
Was the take off location level? Who measured it and how accurate was the measurement? Was the measurement witnessed and verified?
Was the landing at the same level?
Could the plane take off and fly in absolutely still air? (i.e. no Wind Assistance)
Was there any manual or mechanical assistance to accelerate the plane?
Next you have to examine the testimonies of participants and their witnesses, and there ARE questions surrounding these on many early flights.
Next you have to define what "Practical" means when describing a plane, and here you can drive yourself mad, because any single definition excludes types which ARE "practical" in certain use; a Land Plane is not "practical" if its engine fails over the ocean! Are modern military jets "Practical" if their flight control computers fail?
This is why the debate continues!