Real Madrid are a smart club and they have a policy to avoid signing too long contract with old players. I don't think they will break their policy to sign a contract with Harry Kane and even have to spend not cheap transfer cost for that striker. It wipes out all terms in their policy which has been applied in Bernabeu many years.
Between Harry Kane and Mbappe, it's wiser to invest money into Mbappe, not into Kane. Kane is older than Mbappe and even Kane is a world-class striker, he has never played beyond Premier League. Will he be able to adapt to La Liga style? Who knows? At his age, two failed seasons will be like an ending for his career.
Jesulu may only have a short-term contract with Real Madrid as he was the only alternative being considered after Real Madrid lost Benzema. If Real Madrid don't find their best new striker, then they might do it again in another transfer market while following developments on Mbappe's situation at PSG.
Joselu is young and just scored a win goal for Spain to beat Italy in Nations League. However, he is far to be considered as a world class striker. He can improve his skills like Kane did years ago and became a world class striker but I feel he won't be able to do this if nothing really big will change his career.
I am doubtful that Joselu will be able to replace Benzema for Real Madrid as there is big differences in skills and experience of two players.
Joselu himself even spoke in an interview where the content of the conversation was more or less that he said that he was indeed not a substitute for benzema. because he knows the difference in quality between himself and the Real Madrid superstar, Benzema. But Joselu is also a young player whose career can still develop much better. One day he might even become another star player.
And about Harry Kane I think Real Madrid have given up because of the high price it cost to bring Harry Kane to Real Madrid. even though about 2 weeks ago Real Madrid asked Tottenham for a discount regarding Harry Kane's price. but nothing has happened since then. and Harry Kane's name is actually more associated with other premier league clubs, namely Man United. But Man United are also rumored to be giving up their hunt for Harry Kane if there is no price reduction.
I personally feel quite sorry for Harry Kane. he is a star player but he was locked in for quite a while at Tottenham. and don't get much credit.