The question you should ask yourself here is whether all the analogies in question help us understand what the sentence goes on to describe or only one of them is true in this statement.
With that said, consider this:
Situation A: There are 5 people standing in front of you. Only 1 of them is a thief. You go on to say:
One of these people, who is a thief, ...
Situation B: There are 5 people standing in front of you and in this scenario, all of them are thieves. You would say:
One of these people who are thieves ...
In situation A, with the who part you describe a certain single person, whereas in situation B you use it to describe the whole group you can pick from.
The same goes for your scenario.
If of all the analogies you can present only 1 helps you to understand what you want to say, you will use:
One of the analogies which helps us understand ...
If all the analogies you're presenting help you understand what you want to say, but for whatever reason you're picking only one to describe the situation, you'll say:
One of the analogies which help us understand ...