Why do Hebrews, Black Israelites, and SDA’s "feel Jewish"?

I recently had the “privilege” (/s) of speaking to a woman online who is a Seventh Day Adventist. She was so excited about Judaism and said she feels such a connection to the Jewish faith because she doesn’t know anyone else besides other SDA’s who keep the sabbath. She then went into some less fun stereotypes about how she once met a rabbi (complete with long curls – eyeroll) and that she felt so connected to him. It was so weird to see someone get so excited to have to opportunity to talk to a Jewish person and it made me uncomfortable. I felt it kind of racist tbh. If I got excited to talk to a black person, for example, it would not be an appropriate response.

Since none of these religions are actual Judaism (and a large population of Jewish people would regard them as cults), I have to ask: what’s up with them? They all worship Christ. They are very NOT Jewish. So why do they insist they are?