First time 19 y/o filer. My parents received 1400 stimulus for me last year. So I do enter if 1400 even though they received it or can I enter 0 and claim it?

You enter zero since you did not receive it. Be aware of the difference between your parents being able to claim you as a dependent and actually claiming you. If they can claim you and choose not to, you must check the box on your return saying that someone else can claim you. 

If you CANNOT be claimed as someone else's dependent then you are eligible to get the stimulus on your own return even if your parents got it when they claimed you for 2020.

But--- be clear----can you be claimed?   Were you a full-time student in 2021?   That would make a big difference.

https://ttlc.intuit.com/community/dependents/help/when-do-i-have-to-answer-yes-to-being-claimed-as-a-dependent/00/1994319

Thanks! I work full time and am not a student. 

My mom was told since I'm not a student and made over 13,000 dollars than I have to file my own taxes.

@lexi-02 You are good to go...since you are not a full-time student, are 19 and made more than $4300 no one can claim you.  Enjoy the $1400 stimulus !