Otto's approach was teorethically marketed by him ( Vogel Flug etc ), but Wrights were able to see mistakes in it. He wasn't able to control the kite in a way that commercial flying became possible. Also Lilienthal's way to make wings etc were pretty primitive. I see it as a phase that had to be done...to show that man can fly....also Wrights did study his example very thoroughly but invented for instance wind tunnel to measure lift etc.Specifically what are you referring to with the phrase "but later developements did reveal some new ways to comprehend flight more theoretically correct."
Birds are still very very much ahead in several aspects of flight...they are very clever too....I recently saw a crow that bombed a glass vase into the asphalt to be able to get the candle grease out from it.....grabbed it from a local cemetery.