The opening twist of "Secret Invasion" Episode 1 seems to have understandably reshaped some MCU fans' view of Everett Ross. With that in mind, in response to the aforementioned Reddit comment about the MCU character, one fan wrote, "I gotta think the Everett Ross from 'Black Panther' was the real one and this Skrull was a recent replacement." Their response prompted additional comments from other "Secret Invasion" viewers, some of whom debated whether a Skrull can totally impersonate a human being's genetic and biological makeup.
If they can't, then it seems safe to assume the version of Ross who got shot and medically treated in 2018's "Black Panther" was a human being, otherwise Shuri (Letitia Wright) and her fellow Wakandans would have noticed his Skrull DNA. If a Skrull's transformation can trick even those who operate on them, though, there's no telling how long Agent Ross has or has not been a Skrull in disguise. Given the fact that the central Skrull uprising of "Secret Invasion" is a recent development in the MCU, even Ross' previous efforts to minimize conflict on Earth don't completely absolve him of suspicion.
Regardless of what the truth is, fans will probably have to wait for Marvel to confirm the nature of Ross' identity before they know which of their theories about him are correct and which aren't. Either way, it seems safe to say that "Secret Invasion" Episode 1 has already proven to be quite the conversation starter among viewers.