It didn't fit
The Gauntlet altered its size to fit the Hulk's hand. It's possible that it was designed to resize itself for whomever tried to wear it, but it's more likely that Tony was directing the shift using his mental control over his nano-machine suits. If that's the case, then there's no way for anyone who isn't Hulk sized to put the gauntlet on until Tony can get there to resize it.
It's also possible that the power surge from the Stones shorted out the Gauntlet's reshaping capabilities. We never see it do anything other than mechanical movement until after Tony comes into contact with it at the very end (and even then it's not clear whether he was interfacing with it directly or using parts of his current suit to steal from the Gauntlet).
It didn't occur to them
It's very easy to get tunnel vision during high stress situations. Nobody who had their hands on the gauntlet had much time to think critically - they were too busy fighting for their lives. Once it was established that it was vital to return the Stones to their own times, it simply didn't occur to them that the Stones could be used for a different purpose.
They didn't know that they could
Thanos snapped his fingers and killed half the universe. Does that mean that you can snap your fingers and kill a specific group of people? Is there like a dial you have to turn from the "kill half of everything" setting to the "kill the bad guys, but nobody else" setting? Tony has a much better idea about how to control the Gauntlet and use it for his own purposes than most of the heroes who were trying to transport it.
Also, Spider-Man at least (and probably a few of the others) didn't have the stomach to murder an entire army with a finger-snap, even if it would save lives. This isn't universal though, so it doesn't get a header.