Few verses below Ecc 3:18, there is a verse "Who knows the spirit of the sons of men, which goes upward, and the spirit of the animal, which goes down to the earth?" It clearly says the spirit of man and animal is different.
I disagree. The passage says one goes upward and one goes down. However, a few verse prior Solomon states that both man and animal all have one spirit.
18 I said in my heart, "Concerning the condition of the sons of men, God tests them, that they may see that they themselves are like animals."
19 For what happens to the sons of men also happens to animals; one thing befalls them: as one dies, so dies the other. Surely,
they all have one breath; man has no advantage over animals, for all is vanity.
20 All go to one place: all are from the dust, and all return to dust. (Ecc 3:18-20 NKJ)
The word breath here is ruwach, it is the same word for spirit. He says they all have one spirit. I have heard some suggest that the reason the spirit of man goes up and the spirit of the animal goes down is because man will be resurrected and animals won't be. I guess this is possible, but I don't know if it can be proven from Scripture.
"For what man knows the things of a man except the spirit of the man which is in him? Even so no one knows the things of God except the Spirit of God." (1 Corinthians 2:11 NKJ)
"But the natural1 man does not receive the things of the Spirit of God, for they are foolishness to him; nor can he know them, because they are spiritually discerned." (1 Corinthians 2:14 NKJ) (NASB footnoted 1 as 'unspiritual')
People have a spirit, but only fleshly traits can be revealed as two verses (we could find more verses but I just write few of them) say.
What I am trying to say is man is made up of a body, soul and spirit.
I can agree to a point here. According to Gen 2:7 man is a living soul that consists of a body and the breath/spirit of life. The passage is pretty clear in explaining how man was created. The passage says that God formed the man from the dust of the ground.
7 And
the LORD God formed man of the dust of the ground, and breathed into his nostrils the breath of life; and man became a living being. (Gen 2:7 NKJ)
So, man was formed from the dust of the ground. Whatever man is, he is from the dust of the earth. The next thing God did was to breathe into the man. He breathed the breath/spirit of life into the man and the man became a living soul. From this passage we can see that the man existed before God breathed into him the breath/spirit of life. The idea of breathing suggests that something came out of God and into the man. From the passage we know what came out of God and into the man, it was the breath/spirit of life. From this I surmise that man is a created flesh being into which God breathed His breath/spirit of life. This breath/spirit is not man but rather what gives man life. This attested to from other passages of Scripture. In Job we find,
12 Surely God will never do wickedly, Nor will the Almighty pervert justice.
13 Who gave Him charge over the earth? Or who appointed Him over the whole world?
14 If He should set His heart on it,
If He should gather to Himself His Spirit and His breath,
15 All flesh would perish together, And man would return to dust. (Job 34:12-15 NKJ)
In this passage both Neshamah and Ruwach are used, both are Hebrew words for breath/spirit. He said if God retrieved his breath/spirit all flesh would die and man would return to dust. As we saw in Gen 2:7 man is dust as he was created from the dust. David too, acknowledges that man is dust.
13 As a father pities his children, So the LORD pities those who fear Him.
14 For He knows our frame;
He remembers that we are dust.
15 As for man, his days are like grass; As a flower of the field, so he flourishes.
16 For the wind passes over it, and it is gone, And its place remembers it no more1. (Psa 103:13-16 NKJ)
Paul too acknowledges that God gives life to all things.
13 I urge you in the sight of
God who gives life to all things, and before Christ Jesus who witnessed the good confession before Pontius Pilate, (1Ti 6:13 NKJ)
Paul uses a present tense verb here which indicates a present continuous action on God's part. This statement flatly refutes the idea that humans have immortal souls. It also refutes the immortality of angles. According to this passage everything that is alive is living because God is presently and continuously giving it life.
If we are to understand what man is we have to understand all of these passages in such a way that we acknowledge all of them without contradiction. That means taking all of the passages that speak of the spirit of man and the passages that speak of man as dust and bringing them together is a cohesive fashion where this no contradiction. It seems to me that understanding man as a being created from the dust and infused with the breath/spirit of God does this nicely. It can explain all of the passages that speak of the spirit of man and the passage that speak of man as being dust. If was say that man is a spirit being we cannot account for a lot of passages.
I liken man to a computer. A person can build a computer and write a code for the operating system, but unless they apply electricity the computer will do nothing. I liken the electricity to the breath/spirit of God. As the electricity brings life (figuratively) to the computer so the breath/spirit of life from God brings life to the man. Even though the electricity brings life to the computer the electricity is not part of the computer. The electricity is a separate entity that animates the computer, likewise the breath/spirit of God is not a part of the being of man but rather is what animates or gives life to him. We saw from Paul that God gives life to all things and from Moses that that life comes from God's breath/spirit and from Solomon that both man and animal all have one breath/spirit. This all fits nicely with what was stated in Gen 2:7 that man is dust.