Usyk is the best CW of his era and has beaten HW champs and ex HW champs of his era, making him the best HW of his era as well. All a guy can do is beat who they put in front of you, and he's done that. ATG HW? That's tough to evaluate as every other HW that can be mentioned as an ATG HW had many more fights that Usyk. People can talk about H2H fights forever but we'll never know if boxer x from 2024 could beat boxer y from 1940.
I don't think he'd do that with Steward-era Lewis, but Wlad quite possibly. Usyk breaks the top 15 ATGs imo. He really has made a statement, very great fighter.