Who has to file?
the only other thing to contemplate is while you may not be required to file a federal return, did you receive your stimulus payment? if not, the way to now obtain that is filing your 2020 tax return. Also, your state filing requirement may be different (for example, in NC, it is required at $10,000 (single)).
Q. Re: Am i required to file tax? (bank interest, stocks, dividend)
A. No. You heard correctly, that you need to have at least $12400 to file tax for single. That assumes you can not be claimed as a dependent on someone else's tax return. If you can, the filing requirement is only $1100.
There's another thing to be aware of. Stock brokers issue a form 1099-B for the sale. The IRS gets a copy. If the 1099-B does show the gain or loss (that is, it only shows the gross sale amount) there is a chance of receiving an IRS notice of failure to report. But, that is easily explained.
As others have said, for 2020, there is the stimulus payment to consider.