You are a US person because you fall under the "citizen or resident of the US" category because you are a "resident". And you are a resident alien of the United States for tax purposes if you meet either the green card test or the substantial presence test for the calendar year (January 1-December 31). Meaning, you are not a green card holder but have resided in the US for the majority of that year thus making you a resident alien = US person.

Just like undocumented people without DACA, they are still in the same category, a resident alien= US person, because they meet the requirements for substantial presence.

I prepared taxes for a little while so I hope that makes sense to you.