Your cropped photo is of flight on the 17th Dec, and from the complete photo there is no evidence of any slope.
You are a bit in denial.
Just study in detail the best image available (TIFF 17.2 mb). You find it here:
[First flight, 120 feet in 12 seconds, 10:35 a.m.; Kitty Hawk, North Carolina]
This photo in small format was published by the Wright brothers in Sep. 1908 as evidence for their alleged flights in 1903. If the slope had been visible on the small size picture the brothers would not have sent it to be published. Unfortunately, they made the mistake to keep the negative and when this was studied with care the slope in front of the plane revealed itself in its entire splendor.
The slope (the fact that the plane was carried up on a hill before each flight) is also confirmed by John T. Daniels in his 1933 letter to a friend and also in his declaration from 1935.
see:
Eyewitness Account of First Flight by John Daniels