Yeah, indentured servitude is slavery and slavery is very much still legal in the US. There's a reason nearly 1% of the US population is in prisons slaving away for corporate profit.
*That said*, in the context of the colonies and early US indentured servants refer to generally white people serving out a crime or paying off a debt, while slavery is more generally thought of as the enslavement of black people in the south. I'm specifically not conflating those two things.