"Bearer" and JWT are orthogonal. Tokens in other format or stateful formats can be bearer tokens, while JWTs can use non-bearer authentication methods. For instance, RFC 9449 (DPoP) describes an authentication method where you have to provide a PoP (based on JWS) in addition to an access token (which may or may not be JWT).
Bearer token just means whoever has the token string has the associated capability - like bearer bonds.
Unlike e.g. challenge-response or signature authentication.
Oauth defines bearers tokens without requesting them to be jwt.