Because you have no income in 2020 and because you are a dependent on your parent’s return, you likely have no reason to file a 2020 return. The 2020 COVID stimulus payment/Recovery Rebate tax credit is not given to dependents.
For 2021, if you will only have $1000 in income, you likely will not be required to file. (See the latest version of the Form 1040 instructions for the filing requirements, which may or may not be the same for 2021 as they are now.)
However, even if you are not required to file, if you had any federal or state income tax taken out of your paycheck, it may be to your advantage to file anyway, since with your low income you would likely get most of it back as a refund.
It is too early to know what the rules will be for any future stimulus/tax credit, but it is possible that you would be eligible for a refundable tax credit, which would be another reason to file a return.