I think you are
Ferdinand de Lesseps.
Good day, Madam/My name isn't Adam
His first name is Ferdinand, not Adam
I was the man/Who had two plans
De Lesseps came up with the idea for two canals -- Suez and Panama. (This line made me think of Panama because of the famous palindrome "A man, a plan, a canal -- Panama".) More specifically, de Lesseps was a French diplomat who read about the ancient Suez Canal and thought it would be cool to have one again. He had friends in Egypt because of his diplomatic past, and had the influence to make it happen. Later he tried to repeat his success in Panama.
The first one succeeded
In 1869 the Suez Canal was opened and made a lot of money for France (at least it appeared so at first).
The second, also needed/Did not work
The Panama project had problems. Basically it wasn't planned well and had unrealistic assumptions baked in. De Lesseps and his crew ran out of money in 1889.
and at that/A tip of my hat/To the Yanks, who completed/The work that defeated
The US took over the project in the early 1900's (the exact year depends on what you consider "taking over"). The Panama Canal was opened in 1914.
This good man, never odd or even
All I can see here is a description of who was defeated by the Panama Canal, ie, de Lesseps. "Never odd or even" is a palindrome but I don't think it has any other meaning.
Though able was I, I was not quite forgiven
He had to pay a fine and was even sentenced to prison for bribing people related to the Panama Canal. He didn't have to serve the prison sentence but it was still a sign of "unforgivenness".
Afterword: Here is a list of the
palindromes referenced throughout the poem: (I found them unuseful except reminding me of the Panama one, but I could be missing something.)
Madam I'm Adam
A man, a plan, a canal -- Panama
Never odd or even
Able was I ere I saw Elba