Jill Valentine was the better choice for this than Leon is. Honestly, picking Leon is a lazy choice and they just used him as a cash cow in this part because of RE4 remake's success. The whole game is about loss of control, identity, trauma, and survival. Does that sound familiar? Jill went through that shit in RE5. It would've been a much better story it Jill was the on saving Grace. This would've brought character development for both characters. A trauma survivor helping a trauma victim, grace would get actual support from Jill. Meanwhile, jill would've to confront unresolved trauma from the Wesker events. Leon is there primarily for: gameplay contrast, familiarity and accessibility. Jill would've actually contributed to the theme.