But there IS a major timeline change in that Thanos in 2014 JUMPED to the Avengers 'Endgame' present. Putting the Infinity stones back into the timeline won't change that. And IMO that is a BIG temporal WTF as since the original Thanos jumped 5+ years in to the future, he wouldn't be around for the previous battle because he got turned to ashes and couldn't be put back like the Infinity stones.Saw it only once so, I recall them saying the 'future' they came from was their past, something like that anyway. It sounded to me any changes in the past would not change the time they came from, any changes would just create alternate timelines. Since the Time Stone comes back to the Ancient One, nothing changes there going forward. However my memory, the main thrust I took from their time travel talk was changes in the past wouldn't change their future. That Thanos of the past is just another Thanos coming at them. The Avenger's snappy guy still snapped. Sure it's bollocks but I haven't seen a time travel story that wasn't.
So, yes (given Banner's explanation of Time Travel) our MCU timeline occurred the way it did, but banner COULDN'T keep his promise to the Ancient One about not creating alternate timelines as a result of their actions because they COULDN'T place Thanos back to 2014. And hell given how scewed up that timeline now is - maybe Barton should go back into that one and just grab Natasha and 'bring her forward' in the way Thanos brought Gamora
