Why were there many slaves in the Roman state?

During the existence of the Roman state, many wars of conquest were conducted, which ensured an increase in the population. The inhabitants of the conquered territories became slaves. Slaves were a productive force. The owner had the right to dispose of the slave as he wanted, the slave was not considered a person, he was treated like a thing: he could be sold, given. It was also possible to take into slavery for debts, which made slaves out of people who lived in the territory of Rome.