You still are not using that cell bro.
Your argument is flawed because every person doesn't and can't have children.
Think about it this way; GUYS CAN'T HAVE CHILDREN! Dork!
You are implying a one person to one child ratio, which doesn't exist because ONLY women can have babies. (Maybe your father hasn't had that talk with you yet?)
So sport, you have two parents and they have 1.2 kids. They both then die. They have made room for 2 people, but only produced 1.2 people. That, my friend is a negative population growth.
This is why, one-cell man, that When they calculate future population growth they calculate it using an assumed lifespan (avg./mean current lifespan), BECAUSE IT DOES MATTER!
So one last time. Here it is as simple as I can make it without using crayons; the extent that generations overlap (being alive at the same time) is the extent that the population will grow or decrease. The less overlap, the lower the population growth. More overlap, the greater the growth.
Can you hear me now!