Even though Jude Belligham is Real Madrid's top scorer at the moment, in my opinion they need a single striker as a solution to make their front line sharper.
Jude Belling surely is a discovery of La Liga 2023 - 2024 season and he is even doing better than Federico Valverde in the last season. The Uruguayan player did had a good first half of last season but after World Cup 2022, his performance dropped a lot. In early matches of La Liga, Jude Bellingham even played better than Valverde and as a midfielder, his scoring intensity will drop in later months of season. I agree with you that Real Madrid must trigger scoring ability of other attacking players as they can not rely on Jude forever.
Joselu was not an alternative when Real Madrid reached a dead end because his style of play was not as prominent as that of a classy striker. When Real Madrid has a world-class striker like Mbappe, if they succeed in bringing him in, their game will be much more terrifying, like when Benzema, Ronaldo and Bale play together.
Joselu is their best striker now but he is not a world class striker and even in Spain, he does not have a solid position in Spanish national team. It tells us a lot about ability of Joselu but unfortunately, Mbappe still is a story of future and I don't know when he will become a Real Madrid player.
When they face a team that is much more balanced, this is where a quality single striker is needed and Jude Belligham can focus more on helping the attack so that it will produce a terrible collaboration on the front lines. Jude Belligham also may not be able to score every match because of the tight match schedule they face and having a single striker can help.
Jude Bellingham will get more attention from opponents after his latest excellent matches and his scoring intensity. When opponents pay more attention, use more players to control Jude, other attacking players of Real Madrid will get advantage from it.