I've always lived with family and been a student, so apart from odd jobs here and there I've never really worked full time or reached a minimum taxable threshold of income. On top of this, I am currently overseas. What I'm wondering is, am I still eligible to receive a Covid19 stimulus check?
If you have not (and will not) file your taxes for 2018 or 2019 then the only way to receive the check is to file for 2020 next spring. The check is actually an advance on a 2020 tax credit, so you can take it now or later.
However, for this year you have until July 15 to file your 2019 taxes. Even if you have $200 in income for the year, might as well file so you get the stimulus check sooner.
Note that if you are a dependent on someone else's return then you are not eligible for the stimulus check.
Its important to note that the minimum threshold of income to be required to file your taxes ($12,200 for a single filer under 65) is just that, a minimum to be required to file, not the minimum where filing is an option. If you so choose, you can file your taxes with $0 in reported income (or some small amount of money from your odd jobs in your specific case) and thus be eligible to receive the benefits of the CARES Act immediately upon filing.
You first need to determine if you are somebody's tax dependent. The rules for that are outlined in the IRS Publication 501 and you can ask your family to run the Interactive Tax Assistant decision engine relative to the question to double-check. Based upon the facts and circumstances you have presented there is insufficient information to give you a correct answer without first establishing if you are anybody's dependent.