Therefore, just as sin entered the world through one man(i.e. Adam), and death (came to Adam)through (Adam's) sin, and in this way (in the way death came to Adam due to his sin) death (also) came to all people(i.e. us), because all (we, just like Adam) sinned[Romans 5:12]
Note that a comparison is being made here between Adam and the rest of mankind (us). I have divided the verse into 2 parts:
PART 1 (about Adam)
Therefore, just as sin entered the world through one man(i.e. Adam), and death (came to Adam) through (Adam's) sin,
PART 2 (about mankind)
and in this way (in the way death came to Adam due to his sin) death (also) came to all people(i.e. us), because all (we, just like Adam) sinned
What this verse is talking about? The same thing Romans 6:23 is talking about: For the wages of sin is death,
No imputed sin!!! No nature indwelt with iniquity!!! No Original sin!!!