As you said, the same word can have two or more meanings. I'm saying yes, it appears to mean breath in many places. But it can't be exclusively breath, Proverbs 20:27, and animals can breath without it. That's it, 2 reasons.
I agree, it's not one meaning exclusively. Hence we consider the context.
So, it may be best to see if we are understanding the word in the right way, so that the context helps us get the correct understanding of the text.
Here, you can see, a number of different translations.
Isaiah 57:16
New International Version
..
.the very people (neshamah) I have created.
New Living Translation
...all
the souls (neshamah) I have made.
English Standard Version
...and
the breath of life (neshamah) that I made.
Berean Standard Bible
...with
the breath (neshamah) of those I have made.
New World Translation (NWT)
...Even
the breathing creatures (neshamah) that I have made.
Are there any you don't agree with?
If I look it up, the word is listed as spirit or soul, not as the first definition, but as an alternative definition. So yes, I am considering the definition.
No Proverbs 20:27, JW translation is "The breath of man is the lamp of Jehovah". It can't be breath. Breath is not at all like a candle or a lamp, there is very little in common there. It's not even poetic. Then the verse continues: "Searching through his innerost being". How does breath "search"? I've asked this repeatedly. Still no answer.
Sorry. Answer's coming.
Here, we have the different translations on Proverbs 20:27
New International Version
The human spirit is the lamp of the LORD that sheds light on one’s inmost being.
English Standard Version
The spirit of man is the lamp of the LORD, searching all his innermost parts.
New American Standard Bible
The spirit of a person is the lamp of the LORD, Searching all the innermost parts of his being.
Christian Standard Bible
The LORD’s lamp sheds light on a person’s life, searching the innermost parts.
Aramaic Bible in Plain English
The soul of the children of men is the lamp of LORD JEHOVAH, and it searches all the inner rooms of the belly.
Contemporary English Version
Our inner thoughts are a lamp from the LORD, and they search our hearts.
International Standard Version
A person's spirit is the lamp of the LORD; it searches throughout one's innermost being.
Literal Standard Version
The breath of man [is] a lamp of YHWH, Searching all the inner parts of the heart.
Young's Literal Translation
The breath of man is a lamp of Jehovah, Searching all the inner parts of the heart.
New World Translation (NWT)
The breath of a man is the lamp of Jehovah, Searching through his innermost being.
Considering all these translations, I think we can understand the context.
The spirit of man / the breath of man -
what man gives out, allows Jehovah to search out his innermost being.
In other words, your attitude - your spirit... how you say what you say, and do what you do, is like a lamp Jehovah uses to search out the innermost person - the inner man.
Compare Matthew 15:19
For example, out of the heart come wicked reasonings: murders, adulteries, sexual immorality, thefts, false testimonies, blasphemies.
See...
*** it-2 p. 196 Lamp ***
According to Proverbs 20:27, “the breath of earthling man is the lamp of Jehovah, carefully searching all the innermost parts of the belly.” By what a person “breathes out,” or gives vent to, whether good or bad expressions, he reveals, or sheds light on, his personality or inmost self.—Compare Ac 9:1.
*** w63 8/15 p. 502 Understanding What the Spirit Is ***
The Hebrew word for spirit is ruʹahh and the Greek word is pneuʹma. Some Bible translations render the Hebrew word neshamahʹ as spirit at Job 26:4 and Proverbs 20:27, but more careful translations use the word “breath” here rather than spirit. This word neshamahʹ is the one that is used at Genesis 2:7 for the vital breath that was put into Adam at the time of his creation. Its use here indicates that what God blew into the nostrils of Adam was literal breath. However, the active life force that God gave him, causing him to have a conscious existence, was his ruʹahh or spirit. This active life force is not specifically mentioned at Genesis 2:7, but it is referred to elsewhere.—Gen. 6:17; 7:22; Eccl. 12:7.
King Solomon is describing the lamp of Jehovah, and the lamp of the righteous / wicked. That's the connection. There's something in common between these two ideas even without the squabble on translation.
Looks like two different lamps for two different purposes... applied in two different ways.
Because of the context of the chapter, and the way the words are written, the two consequences are inverses / opposites of one another.
If the one phrasing is "soul death", then the other very similar phrasing would be "soul life".
The whole chapter is comparing he wicked to the righteous as opposites. The repetition is a tiny bit tedious, but at least it's precise. This isn't allusion and metaphor. It's straight-up law directly from Jehovah.
It's interesting to see the choices made compared to the others.
See
here. Then see
here.
Same Hebrew word. Different word usage. Both correct meaning. One is person. The other is life.
nephesh: a soul, living being,
life, self,
person, desire, passion, appetite, emotion
On another occasion, the context may render the usage as desire, or emotion, or living being, etc.
I agree it's not as strongly supported as I had thought. Of course I trust the opinions of Rabbis over many centuries who speculated about this. I'm happy to have found a thread connecting it to the text.
Well, if you trust their ideas, would anyone pointing out anything the Bible has to offer that's different, change that?
King Solomon is depressed.

Jehovah said I can "surely live" if I return? I'm back to happy!

That's how I fit it. Jehovah trumps King Solomon.
See what I mean?

It's not only the Rabbis. You probably trust yourself also. Right?
You did not answer the question though, did you.?
Speaking of the dead. Not the living. Can this soul/spirit think, and act... when you die?
How do you fit that with
Ecclesiastes 9:5 and
Ecclesiastes 9:10?
This is a fact finding mission. I'm on the hunt!
That sounds good.
...but how can that be, if you trust the Rabbis speculation, and your interpretation?
Let me test that out. Try
this, then let's hear your thoughts.