Taking the human sperm and egg of which each has 23 different chromosomes making a total of 46 chromosomes when they are combined you have a human, and you can never take those 46 chromosomes and produce anything other than a human.
Based on what criteria?
I liked the way you parsed your words 'may very well be' differences between them and there may not be differences. But I am inclined to believe there would be differences as their diet would be different and their living conditions would be different.
Are chimps and humans different because our diets and living conditions are different? If we started living in the water like whales do, would we start giving birth to whales?
Or are the differences between species due to DNA base differences in their genomes?
The day you are born you begin to die.
The Dna information in the cells will control your growth. It will not make you go from fat to skinny that is controlled by you and the input of food into your system.
But a human getting old and creped and dying is only change to that human body and will never cause it to be or produce anything but a human body with joining of sperm of a human male and the egg of a human female.
At what precise nanometer does someone go from being short to being tall, and how do you justify that precise height?