The character was created for the TV show, but was later integrated into the DC universe; the article to which I linked noted that it’s believed that the character will be appearing in the upcoming Black Adam film.
She has been a character in the show Legends of Tomorrow for a couple of seasons. They may have used the name Isis once or twice. The name has become more problematic since the 1970s. They just call her by her first name.
If I recall correctly (and I may not, I watched decades ago), the idea was that the necklace she found essentially made her an avatar of Isis, able to wield the powers of the goddess after invoking it.
I loved that show. One of the first times I saw a woman hero/superhero.
True, but DC has changed character names before (see Captain Marvel → Shazam), so even if one didn’t change the character’s backstory, it’d certainly be possible to have her take on a different superhero name, if they felt it was necessary.