God wants us to be fruitful and multiply, but again like all the commandments, they must be understood through the life of the spirit rather than through the death of flesh. God does not want us producing more little Adams after the flesh, anymore than God is not upset if we press elevator buttons on the Sabbath. God's commandments are to be understood in spiritual terms, not according to the flesh:
1 Cor 7.17-24
But to each one as the Lord has apportioned. As God has called each
one, thus let him live—and thus I order in all the churches. Was
anyone called after being circumcised? He must not undo his
circumcision. Was anyone called in uncircumcision? He must not become
circumcised. Circumcision is nothing and uncircumcision is nothing,
but the keeping of the commandments of God. Each one in the calling in
which he was called—in this he should remain. Were you called while a
slave? Do not let it be a concern to you. But if indeed you are able
to become free, rather make use of it. For the one who is called in
the Lord while a slave is the Lord’s freedperson. Likewise the one who
is called while free is a slave of Christ. You were bought at a price;
do not become slaves of men.
Each one in the situation in which he was
called, brothers—in this he should remain with God.
Thus ignoring the flesh includes even things like whether someone is a slave or is free, whether someone is circumcised or uncircumcised, whether someone is single or married. Each of these Paul puts into the "flesh" or "commandments of men" bucket, as opposed to the commandments of God. Everything in the "commandments of men" bucket is neither good or bad. It's just irrelevant. It "counts for nothing". Thus we should pay as little attention to it as possible, as our focus should be on doing the work of God.
God is spirit, and those who worship him must worship in spirit and
truth. John 4.24 (ESV)
Indeed we are told:
Matt 3.9 (ESV)
And do not presume to say to yourselves, ‘We have Abraham as our
father,’ for I tell you, God is able from these stones to raise up
children for Abraham.
And that's what God wants when it comes to being fruitful and multiplying - to raise from the stone of Christ children for Abraham through faith, and from the followers of Christ, little stones, more children for Abraham. That is, he wants us to produce more spiritual offspring. Here is Paul again in 1 Cor 4.15:
For though you have countless guides in Christ, you do not have many
fathers. For I became your father in Christ Jesus through the gospel.
So it's clear that Paul (and the early Church) understood that the commandments of God are spiritual commandments, not for the flesh, and the commandment for believers is to multiply by creating spiritual offspring. The seed that we are to spread is not our seed after the flesh, but the word of God:
Matt 13.1-9 (ESV)
That same day Jesus went out of the house and sat beside the sea.
And great crowds gathered about him, so that he got into a boat and
sat down. And the whole crowd stood on the beach. And he told them
many things in parables, saying: “A sower went out to sow. And as he
sowed, some seeds fell along the path, and the birds came and devoured
them. Other seeds fell on rocky ground, where they did not have much
soil, and immediately they sprang up, since they had no depth of soil,
but when the sun rose they were scorched. And since they had no
root, they withered away. Other seeds fell among thorns, and the
thorns grew up and choked them. Other seeds fell on good soil and
produced grain, some a hundredfold, some sixty, some thirty. He who
has ears,[a] let him hear.”
But while we are trapped in the tents of flesh, we still have some practical needs to consider, but for Paul this was clearly a concession for expediency, because marriage interfered with the work of the gospel:
1 Cor 7.29-23 (LEB)
But I say this, brothers: the time is shortened, that from now on even
those who have wives should be as if they do not have wives, and those
who weep as if they do not weep, and those who rejoice as if they do
not rejoice, and those who buy as if they do not possess, and those
who make use of the world as if they do not make full use of it. For
the present form of this world is passing away. But I want you to be
free from care. The unmarried person cares for the things of the Lord,
how he may please the Lord. But the one who is married cares for the
things of the world, how he may please his wife, and he is divided.
And the unmarried woman or the virgin cares for the things of the
Lord, in order that she may be holy both in body and in spirit. But
the married woman cares for the things of the world, how she may
please her husband. Now I am saying this for your own benefit, not
that I may put a restriction on you, but to promote appropriate and
devoted service to the Lord without distraction. But if anyone thinks
he is behaving dishonorably concerning his virgin, if she is past her
prime and it ought to be thus, let him do what he wishes. He does not
sin. Let them marry. But he who stands firm in his heart, not having
necessity, but has authority concerning his own will, and has decided
this in his own heart, to keep his own virgin, he will do well.
Thus Paul allows some ministering to the flesh in order to avoid sexual immorality, which would also interfere with the work of God.