Some Can Be Helped

However, you will ~never run into one, because they've already been helped.

If someone doesn't want to be helped, it's impossible. Not even the heavens can help them. 

If someone wants to be helped, it's easy. So easy that, even in the ultra-rare case you run into someone who you can help, if you miss the opportunity, they'll just be helped by the person next to you. It's very much not an issue. You can go ahead and never worry about it. 

Folk will beg for help sometimes. Normally this is a scam. They're a madman who will sabotage whatever help you offer. Helping someone who truly wants it is easy, so they don't get to the begging stage. Often they don't even have to ask in words; they just make puppy dog eyes briefly and then the process handles itself. 

There is an extremely rare edge case where someone wants help but the help itself is difficult. I've never personally seen one, but it is possible, so it must happen. This would be the time to turn away from mortal help and toward divine assistance. It's not like it would be impossible for mortals, but finding the right mortal would be prohibitively tricky.