How can you make that statement after looking at a
model of Pearce's aircraft on a public monument?
Pearse made several attempts to fly in 1901, but due to insufficient engine power he achieved no more than brief hops. The following year he redesigned his engine to incorporate double-ended cylinders with two pistons each. Researchers recovered components of his engine (including cylinders made from cast-iron drainpipes) from rubbish dumps in 1963. Replicas of the 1903 engine suggest that it could produce about 15 horsepower (11 kW).
Verifiable eyewitnesses describe Pearse crashing into a hedge on two separate occasions during 1903. His monoplane must have risen to a height of at least three metres on each occasion. Good evidence exists that on 31 March 1903 Pearse achieved a powered, though poorly controlled, flight of several hundred metres.
Pearse himself said that he had made a powered takeoff, "but at too low a speed for [his] controls to work". However, he remained airborne until he crashed into the hedge at the end of the field.
With a 15 horsepower (11 kW) engine, Pearse's design had an adequate power-to-weight ratio to become airborne (even without an aerofoil). He continued to develop the ability to achieve fully controlled flight. Pearse incorporated effectively located (albeit possibly rather small) "ailerons". The design's low centre-of-gravity provided pendulum stability. However, diagrams and eye-witness recollections agree that Pearse placed controls for pitch and yaw at the trailing edge of the low-aspect ratio kite-type permanently stalled wing. This control placement (located in turbulent air-flow, and close to the centre of gravity) would have had minimal, possibly inadequate, turning moment to control the pitch or yaw of the aircraft. The principles of his design, however, accord precisely with modern thinking on the subject. The Wright brothers, in comparison, successfully applied the principles of airfoil wing-profile and three-axis control to produce fully controlled flight, although their design, using wing-warping and forward mounted stabilizer, soon became obsolete.
I believe the Wrights claim to fame is a fabrication by the "interests" that negotiated the return of the Wright Flyer in the 1940s.
I am not even sure Richard Pearse was the first. I seem to recall reading of (I think) a Frenchman who achieved heavier than air flight around 1899 or 1900, but can't find the reference now.
Of course, the various proponents usually start "hair splitting" arguments over definitions of "powered flight" "controlled flight" or as we see above, "official witness". There was no handbook or manual on the principals of flight pre 1900, no book of proven aircraft designs. Any man that built a successful "flying machine" around 1900 had to be something of a pioneering aeronautical genius!
I think of the definition of first/early flight as the ability of a heavier than air machine to climb above the ground and fly in level flight, from which the pilot survived without broken bones.
There is one intriguing common aspect relative to Richard Pearce, Wilbur and Orville Wright and Harry Ferguson (who built and flew the first aircraft in Ireland and later developed the Ferguson tractor) - they were all bicycle mechanics with their own bicycle repair shops!!