I don't think if Joselu was the alternative player for Benzema because the most important thing about Joselu is his age and he is not younger than Benzema to take his place in Real Madrid for years and On the other hand Joselu was never on the same level with a player like Karim Benzema.
Real Madrid needs a player like Mbappe or other young center forwards to make them sure in the next seasons.
Real Madrid thought he could replace Benzema, but he wasn't as good as they hoped because Joselu was not performing as well as Benzema. He performed well in Espanyol, but I noticed Joselu struggled to build chemistry with another player in Real Madrid.. Joselu was not being a starting line up of real madrid. Ancellotti puts him in the starting lineup in the first match but after, ancellotti is aware of how bad the performance of joselu. I rarely seeing him become starting line up again.
There's no choice for madrid than buying a new striker but since the club linked to the mbappe and i think that it will be wise for us waiting for the confirmation from real madrid. Mbappe is yet to extending his contract with PSG.
Madrid is still having a chance to get him next year caused by mbappe's contract gonna expire soon. The close of summer transfer window is very close.
Madrid doesn't have a lot of times in searching a new striker.