Who really created the first Batman?

There is evidence that this Batman drawing, dated 1932, was the real inspiration for the Batman attributed to Bob Kane.

It is established fact that Frank D. Foster II drew this original Batman in 1932 and in following years showed it around to the major comic publishers in New York. He was turned down by them all. But the Batman that appeared in May,1939 caused Foster to claim "They stole Batman!"

Could the assumptions of more than 60 years be wrong?

In his autobiography, “Batman and Me”, Bob Kane claims how one of the main inspirations for his Batman came from the flying bird-man created by Leonardo Da Vinci. But Da Vinci was not the only artist whose work might have influenced Kane’s Batman.

Original Batman