Why did so many of the original Jamestown colonists die within the first year of its settlement?

The main cause of death was starvation and disease.

Most colonists weren't farmers and didn't know how to use the land. And some were killed by foreign diseases.

Plus add on the fact that native tribes weren't so happy with them, and declared war.

the roman republic began to expand when rome fought the punic wars and defeated carthage. the punic wars refer to the series of 3 wars fought among rome and carthage, before it ended in carthage's defeat.