My stance is that before you embark upon writing your own mythology retelling, you should actually read the source literature you're basing your retelling on as opposed to simply relying on other retellings.
And this is NOT gatekeeping. Not when I’ve got all the material at @arthurianpreservationproject at least for Arthurian Legend. Many translations of Greek myth are available on the Internet Archive as well.
Everyone has bias so basing your stuff on retellings is not only taking someone else’s interpretation at face value, it’s in poor taste. Read the myths and form your own opinions and ideas. Wikipedia and blog posts are not sufficient if you intend to adapt for yourself.
To add to this, not only is this not gatekeeping, this is pushing the gate wide open. This is telling artists to go explore and frolic in the pastures and ancient woods beyond the fences.
As ever, I'd like to direct people to this quote by Michael Moorcock:
To this day I advise people who want to write fantastic fiction for a living to stop reading generic fantasy and to go back to the roots of the genre as deeply as possible, the way anyone might who takes his craft seriously. One avoids becoming a Tolkien clone precisely by returning to the same roots that inspired The Lord of the Rings.
The same applies to retellings (and adaptations, for that matter, since one user brought it up in the tags). For example, you are less likely to write a TH White clone if you go and read Malory for yourself, or for that matter go further back to Malory's own sources such as the Vulgate Cycle. Another example, you are less likely to become a Madeline Miller clone by reading Homer's Iliad and Odyssey for yourself.
And for heaven's sake, don't do what I did as well for years which was rely on summaries and articles. Try and go as in depth as you can, and face the work on its own terms (but don't be intimidated by its age, either).
Because as Ragnelle said above, by approaching these works by yourself, you will likely come to your own conclusions and not just parrot someone else's. Ideally as well, you will be less likely to end up parroting tired and terrible tropes (particularly racist and misogynist tropes) that have their origins in other people's retellings, as well as flanderisations of the characters and misinterpretations and generalisations of the stories themselves brought about by pop culture.
