@Kurne - she was around 10 in AMATW?? 15 is a believable look then. Girls these days tend to look much older than they really are.

@HeavyMetal4Life - I thought he was gonna say the famous, “As long as one man stands against you Thanos, you’ll never be able to claim victory.”

Would’ve been icing on the cake.

@gulducati - So true, I think in essence they still told that speech only they did it through visuals. It's clearly something that every knowledgeable fan would instantly think of.

@JonC - he wasnt back with Peggy in the 30s, especially because we know when that song came out.

You've got to imagine that they dealt with the "original state" of the stones off screen.

@Chewtoy - that is a great point right there. Common sense logic!!

@Chewtoy - "you're embarrassing me in front of the wizards"

But yes, you're totally right. And I've said before multiple times that the time and reality stones could fix the state of the other stones, so we on the same wavelength here lol.

@HeavyMetal4Life - Plus he had Mjolnir, granting him the Power of Thor, which means Steve was probably strong enough to wield and use a ton of the Infinity Stone’s collected power.... combined with the Sorcerer Supreme’s knowledge and abilities, possibly even all together without crippling or killing himself.

@Skwib - I'm glad others keyed in on how Cap brought the Stones back to their places of origin. I thought of ways after the movie he could have done this, and it's not THAT complicated.

First stop is to the Sanctum Sanctorum. With the help of the Ancient One and the Time Stone, he could have reverted the Space Stone back to the Tesseract, and the Mind Stone back into the scepter. With Frigga's help, he could have had her re-insert the Aether back into Jane. Since the Soul Stone was acquired, there's no reason for the Red Skull to guard the mountain on Vormir, so Cap probably didn't run into him bringing it back. That leaves Morag. The Avengers had the Orb casing so, put the Power Stone back in it and good to go. War Machine knocked Quill out, but Cap could have either stalled Korath as Peter gained consciousness or revived him himself.

As far as other timeline improbabilities, such as 2014 Thanos getting killed and Nebula shooting her past self, there are two explanations:

1. Iron Man used the Gauntlet to not only dust Thanos but to restore the 2014 timeline to prevent a paradox.

2. Quantum entanglement. In quantum physics, particles have been proven to exist simultaneously in different locations at the same time. Perhaps with the time travel shenanigans, and certain quantum physics being flooded into general physics from the time hopping, some aspects of quantum entanglement "fixed" the timeline and allowed for Endgame Thanos and 2014 Thanos to exist simultaneously without causing an alternate reality.

And all that said, when Cap stayed back in the past, I'm sure he made quite the effort to let events play out. Maybe he became a therapist or something -- a way to contribute that didn't require punching stuff. We also don't know how long it took him to put the Stones back. It could have been years, if not decades.

@Victorg1983 - Half his class was dusted. So yeah... why wouldn't he be back in high school. And considering that half the population wiped out, including half the teachers and administrators and all of the societal disruptions, I would guess it would be two years before even the non-dusted students went back to class. Heck, Scott Lang is running around San Fran 5 years in with garbage all over the streets. The Snap would literally stop everything in its tracks and life would essentially be on hold in all sorts of ways as people picked up the pieces.