Even The Hulk is semi-cannon to the MCU. The Incredible Hulk begins with Bruce in Brazil, while The Hulk ends with Bruce in Brazil. With the exception of the slight change in origin (to match the TV series origin, strangely enough) and the total re-casting, The Hulk functions as a prequel to The Incredible Hulk. The only characters that are re-used -- Bruce, Betty, and Thunderbolt Ross -- are essentially the same characters (Betty even remains a scientist who worked with Bruce on the project, which was a unique change from The Hulk), and none of the other characters from The Hulk have shown up in other canon MCU projects (Talbot shows up in Agents of SHIELD, but that's no longer canon).