Avengers endgame messed up in their timelines

Avengers endgame would have been a great movie of all time, not just monetarily but also in story line. But they horribly messed up in the script writing of the time-travel scenes.

It was ant-man’s idea because of his experience in the quantum realm to travel back in time. It took the great minds of Tony Stark (Iron man) and Hulk (Bruce Banner) to make it a reality. But Tony Stark decided that he would agree only if the time travel will not affect what has happened in the last 5 years because he already started a family. So instead of rewinding time, they decided that once the infinity stones were gathered, hulk will snap his fingers and bring back all that was lost 5 years back into the current time.

So where is the blunder?  Well well well, How the heck did the Thanos of the past travel to the present. He did not have the time machine and not even the time stone.  So?????

I suppose, I am not the only one who saw this ugly mess. Marvel producers saw it.

Now the writers of endgame are busy covering up this big mess. Now they explained that Thanos managed to get his hands on the “pym particle” that the avengers used for time travel. Really!!?? He was able to bring back his hoard army back from the past?? Himself and a few dozen helpers maybe. Just maybe. But bring back mighty ships and thousands of his allies from different parts of the universe? Hey I am pretty gullible when it comes to the imagination but this one is just too much. It makes me want to throw up.

However, since I am a marvel universe fan, I am willing to accept whatever reasons the creative writers come up with. Because after all everything and anything is possible in the universe.