Then you should just tell him, you, the carry, fail to carry the game. End of game story.

To raise the rank, either core or jungle. When you decided to support, you just gave the game fate to core. Main question is, can they carry you? Fact is, you just meet them few minutes ago.

Mostly I choose core over jungle, you can see a lot of jungle spent 30 minute in farming rather than control the lane. Especially come to 3k, everyone is a farmer.

Alternatively, pick a snowball hero.