The Marvel Cinematic Universe has grown to become the biggest movie franchise in the history of the industry, but it certainly had a head start thanks to the decades of comic books that preceded it. Building from characters and stories that already had huge fanbases, Marvel Studios had a lot of source material to draw from.
However, the franchise has always taken certain creative liberties with these properties, often either adding new details or omitting important aspects from the original comics. This can either be a blessing or a curse, depending on how the audience perceives such a change.
Iron Man 3's Mandarin for example, was one of the most divisive aspects of the entire MCU so far, as it offered a radical departure from the source material, but there have been more than a few times such changes have been positively received almost unanimously by audiences.
From iconic story lines, to character histories and backstories, and even their design and costumes, there is seemingly little that Marvel Studios are not open to changing. At this point, it's pretty clear that the franchise knows what its doing, and most decisions to ignore the source material are made for very good reasons.
This standard nerd combines the looks of Shaggy with the brains of Scooby, has an unhealthy obsession with the Marvel Cinematic Universe, and is a firm believer that Alter Bridge are the greatest band in the world.