dnd 5th – How to get my players to better engage in the game?

I have a group of 5 players who split into 2 camps. Either they actively engage in the game (LE Warlock and CG Ranger have formed a frantic couple and actively engage in the character) or they are incredibly passive about their engagement.

There are three players who spend a lot of selfless time except when fighting, totally ignoring the role-playing aspect of D & D. I already explained to them that it was new to the game, but that Is something that I actively want to help overcome.

The first is a rogue character who does not want to engage for character reasons, which I understand but can be really disturbing if he refuses to do anything actively with others, or is really passive and just follow the group.

The second is a bard who uses his character almost exclusively to force his members to enter the game. This can be very amusing, but they do not have any character developed outside of "I play despacito" or other references to common memes.

The third is the one that annoys me the most. The player is experienced and his character is an archetype of barbarian dimwitted. He refuses to get out of his phone and must often be called several times before realizing that it's his turn (even in combat!) And it slows the pace of the game a lot. I do not know how to approach this without talking about it. outside the game and without mentioning how much it bothers me / distracts me.

I would prefer some ways to approach this game and allow them to develop their characters and their relationships, but I'm also delighted to approach it from the outside of the table if it's a better one idea.