The Marvel Cinematic Universe changed comic book movies forever when it showed how an interconnected universe could work on the big and small screen. Since then, other movie studios have attempted the same thing to varying levels of success while the MCU fleshed out a growing timeline. Being that the stories evolve with each movie, it wouldn't be until Captain America: The First Avenger and Captain Marvel those prequels became a narrative tool. But telling stories set before 2008's Iron Man meant there were two ways to watch the franchise -- release order and chronologically.
Source：https://www.cbr.com/mcu-timeline-order-black-widow-protagonist/
