If we are to place that verse in context, we have to go back to the first three chapters.
Chapter 1. Jews are guilty of sin.
Chapter 2. Gentiles are guilty of sin
Chapter 3. Both Jews and Gentils are guilty of sin. Thus, All have sinned and fallen short of the glory of God.
This All is within the context of nations. It is not at the individual level.
The verse you posted in chapter 5 simply means all will die due to the singular event from Adam. It do us not attest to the sinfulness of every human born.
The all you underlined referenced the same all in chapter 3. It is at a national level, not the individual level.
With this verse in its proper context, I do t see how it supports your assumption. Please correct me if you believe I am in error by showing me my error.
We need to be very basic. God is a just God. That very specifically means that He will not judge a human for another humans sin. Physical death is not a judgement, it is a result. Eternal death is a judgement, not a result.
Judgement implies a judge made a descision on something. If there is nothing to judge, then a person does not get judged. We know that it is appointed for man to die and to face judgement. All men, not just some.
Now, we know that those who are judged will be only split into two groups. Let's call them 'right and wrong'. The right ones go into Gods kingdom, the wrong ones into eternal death.
So, the only way someone does not go to the wrong place is one of two things. They are not judged or they are judged and found right. We know the first cannot be, so that only leaves the second. The only way into the kingdom of heaven is to be judged right.
The only way to be judged right is to be found 'right' in Christ. Infants are found right in Christ. But the only reason why they are is because they need to be. If there was no need to be found right, there would be no need to be found in Christ.
Why would an infant need to be found in Christ? Simple, because they were born with the propensity to sin - even if they never reached a point where they 'practiced' that ability.
Sin is missing the mark. Children come into this world, from the moment of conception, unable to hit the mark. It is proven that not a single human could ever hit the mark. So, even if an infant was to live until adulthoood, they would never hit the mark. No one can.
That is why they need a Savior. That is why they are safe in Christ. God is a just God, a God of Salvation - not condemnation. Infants are saved because God is just - He cannot judge a human to eternal death who does not choose it. Therefore, a child who did not choose right or wrong - cannot be judged to eternal death, but they need a Savior because they cannot hit the mark.
I know that's a lot, and we can break it down if needed.