The rule or command of death is the issue before us, and Paul is saying some very important things to help us understand it. Sin entered the world when Adam rebelled against God. He was placed in a bountiful garden. God made one restriction that he should obey, and man rebelled against God with his eyes open, knowing exactly what he was doing. The result was that sin entered his experience, and because of that death reigned.
Sin is the consort of death, and everywhere there is sin there is death.
That doesn't even mean that we all have sinned experientially in our lives, but that we all sinned in Adam somehow, that from God's perspective we were present in Adam even though uncounted numbers of years have intervened between that first man and us. Every one of his descendants was present with him and sinned when he sinned. If you have ever stood between two mirrors, you know that if you cock your head to one side you see an infinite series of reflections as the mirrors keep reflecting each other in smaller and smaller images. That is a bit how I picture what Paul is saying. Adam was the first mirror, but you could see every person that would ever be in Adam stacked up behind him, all of us just like him and participating with him.