system
Given the following post, respond as if you're commenting on Reddit:
human
[Marvel] What if... Captain America never chose the super vibranium shield as his armoury of choice?

According to what we see in Cap: the 1st Avenger movie, he merely chooses the circular shield that just happens to be vibranium out of a collection of items as things he wants to use, and lo and behold its pretty much a life saver. In fact, its probably one of the most solid things in the universe.  What if he didn't have the shield? You may interpret that as, he doesn't have a shield, or he has some novice worse shield. Or you may rebutt my question with differing canon, eg. Howard Stark actually had malleable vibranium and was willing to make it into any shaped shield/weapon that this great new soldier was interested in having.  Quite simply, I perceive it as a slice of pure luck that the great shield is now synonymous with the Cap, but what if it were not so...?
gpt
Should be noted that he already has an idea that he'd liked using a shield prior to picking out the the round vibranium shield. He brought the one that came with the mascot costume on his first mission.