Tim McCanlies, Ted Elliott, and Terry Rossio’s draft included a Nick Fury cameo that was meant to set up the character’s solo movie. [Now, Nick Fury is getting his own Disney+ series.]

Alfred Gough, Miles Millar, and Jeff Vintar’s revision introduced the Mandarin as the main villain. [A fake version of the Mandarin was the villain in Iron Man 3, but the real Mandarin appeared in Shang-Chi and the Legend of the Ten Rings.]

Finally, in David Hayter’s rewrite, Tony Stark decided that Stark Industries should stop producing weapons, which angered his still-living father, Howard Stark. So Howard teamed up with his son’s biggest rival, Justin Hammer, and became a villainous version of War Machine. [Justin Hammer appeared in Iron Man 2.]

New Line Cinema expressed interest in having Joss Whedon as director before deciding to pursue Nick Cassavetes. 

Source: https://www.buzzfeed.com/kristenharris1/early-mcu-plans-changed