What is womanly? What is manly?

Words, to the listener, mostly mean what the listener thinks they mean, in my experience. Consequently I often check that they have properly understood my meaning.
I know a number of men who wouldn’t think swinging a punch was in any way a manly thing to do, because a proper manly man is able to exercise restraint. So your interpretation of manly certainly doesn’t square with theirs.

That's how I see it too shedbuilder

But words mean what they mean, not what we'd like them to mean in an ideal world, and you don't have to look far to see that a manly man, or a proper man, has always been the kind of man capable of swinging a punch. Indeed men who can't/ won't do that are even to this day often deemed unmanly, even if that word isn't actually used. How often do we hear of shy, quiet, gentle boys and young men being toughened up ('We'll make a man of you') by being sent to judo classes or boxing or soccer. Indeed, it brings us back to transgender issues and all those transwomen who as little boys were attracted to dolls and dressing up and hanging out with girls and thought they must be girls/women because they didn't fit male stereotypes.

Lots of manly men prove their manliness by knocking other people about.

It depends on your interpretation of manliness. Mine wouldn’t include a propensity to mindless violence.

Why is it helpful? I'm really surprised posters think there is a need to describe what happened as "manly".

This has reminded me of the time I saw a pizza delivery guy get knocked off his moped on Highgate West Hill. It was drizzly evening and I took off my coat and covered him to stop him getting wet. Another woman dialled 999 and another couple of women stopped the traffic and then directed it around him. We had everything under control by the time a couple of men got involved. The men didn't offer me a coat or suggest I put mine back on and offer to cover the victim with theirs. Does this mean I was more manly than them?

OP, you seem to have old-fashioned gendered ideas of how men and women should behave. The 'mensch' comment indicates where that comes from. Lots of manly men prove their manliness by knocking other people about.

I'm wondering if the OPs thinking around this may derive in part (a) from having a granny who could use the word 'mentsch' and then (b) seeing this as more or less synonymous with 'manly'. It appears it should be an ungendered term despite the syllable 'men' - 'man' meant 'human' in old English, mensch likewise in German.

Mensch (Yiddish: מענטש‎, mentsh, derived from German: mensch, 'human being', from Middle High German mensch, from Old High German mennisco; akin to Old English man human being, man) means "a person of integrity and honor."

I can't see that it is helpful at all ; quite the opposite. It is imposing gendered ideas where it is completely irrelevant

Having slept on it and looked up a few Dickens quotes (there’s a particularly affecting use of the word womanly in a description of Nancy in Oliver Twist), I think these words are as someone upthread suggested, primarily about virtue and secondarily about physical characteristics.
I think it’s nice that we can describe both sexes as womanly or manly as far as their best characteristics are concerned. Kindness, patience, tolerance, courage and fortitude can be found in both, but perhaps in different flavours. A man will never have to find the courage to face childbirth, but he will have to find courage of a different sort to support his wife or partner through it. In times past, a man might be more likely to have to face physical danger in his job, or in combat. (Though it would be nice to ignore what are now called gender roles, they do exist and are unlikely to disappear.)
As far as physical characteristics are concerned, a woman’s body develops from girlish to womanly (in most cases), and a man’s from boyish to manly. It signifies maturity, as does the development (one hopes) of the characteristics mentioned above.

So? It's just an example of the kind of use of the word manly she was trying to describe. A helpful one IMO as it's a bit different than the english sense of manly and it clarified what she was trying to say.

The actual character of the guy isn't important.

I don't see that it's relevant at all whether anyone else would have done it, it was the grandmother's comment that was the point of the anecdote.

Again, no disrespect to your friend but I also strongly disagree that most people would not have done this.

It was the obvious, sensible thing to do but it hardly merits being reported back as being "a mentsh".

Yes, I think that's the idea too, then.

In another setting, someone might say, "ah, that man/woman who helped that person was very humane".

In this case you are saying, essentially that they are a very good example of a man or woman. I would say that it is probably not a really common way to use the words in English but it might happen in certain contexts.

I don't think I have a problem with that usage, or think it is sexist. Some people would prefer humane because it doesn't reference our sex, but I don't think it's necessary to pretend that sex doesn't exist, that we are not good men or good women. It would also be fine to talk about good people, but I've become wary of people insisting that it is better or necessary to speak that way.

In that case, I think that it would be similar to when we talk about something like English values. What makes decent English values is probably very similar to what the French thinks makes decent French values. But a French person wouldn’t want to be told they have decent English values, because they are proud of being French. In the same way I don’t want to be called a decent manly woman because I am proud of being a decent woman, even though it is very similar to being a decent man!

OP, is what you are describing a bit like in films set in the Georgian period?

Where if a woman acted in a very calm and kind manner she would be described as a ladylike woman and if a man acted in a calm and kind manner, he would be described as a gentlemanlike man?

So the behaviour is the same but the adjective is different?

That her grandson would be a good person to have at an accident scene?

That despite being gay he has good qualities?

Hmmm. I'm a woman. I have often been told that I walk and run like a man.

Does that help? I'm a manly woman in that sense?

So is that what is happening here? Are you attempting to be poetic OP? Given that we are on the internet, I am not misreading body language.

As far as I understood it, you were asking why people didn’t use the word womanly to describe men, but people were confused by what you thought manly and womanly meant.

The confusion lay in a. you describing someone dealing calmly with an rta as manly and b. you saying manly and womanly traits are often the same.

Do you want to try and explain further what you think the words mean? I am quite happy for your meaning to be wholly subjective, as long as you actually give a meaning of some kind.