The first Resident Evil (reboot) movie should've been a survival horror mystery film. Jill should've been our protagonist, and we should've followed her journey through the estate as she/we uncovered the mystery behind this creepy ass mansion. IMO that is the proper way to reintroduce audiences to the franchise.
You could almost treat it as a coming of age story (for Jill), as the events of the film change her. With elements of B-movie horror, and more than enough monsters for some crazy fun (& scary) set pieces (Lisa Trevor, Plant 42, Tyrant/Wesker), THAT'S your reboot movie.
Leave Birkin, G, Mr. X, Leon & Claire for the sequel, where they can be properly fleshed out. The story of William Birkin can support an entire film on it's own, and it deserves it's own film.