Another one that history overlooked for a long time was Jacob Ellehammer from Denmark . Around 1913 he was flying his co-axial helicopter .... his was not the first helicopter of course but he incorporated cyclic control similar to modern day machines. He was a clockmaker by trade and was a competent machinist & fabricator.
History overlooked him because there was no "proof" his machine actually flew until many years later a picture was found showing a hover demonstration in front of Denmark's Royal Family and was determined to be around 1913 - 1914
During the early 1900's he also built his own radial engine and was flying his own fixed-wing plane around 1907 ..... almost parallel to The Wright Bros first flights. However he was never looking for publicity , simply experimenting his ideas , flew on a remote level sandy beach with few (if any) witnesses.
Trivia: Aprox 1995 when the internet was full of good stuff .... the great great great grandaughter of Ellehammer was a university student ..... Danish students had their own websites and she did an excellent history site based on all Ellehammer's notes and paperwork the family had preserved. . I was in contact with her many times and encouraged and thanked her for what she did. .... Alas none of it survived , probably when she finished university her website was closed.