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.
Is 33 years old young enough? I think you are wrong, this age is the end of a career when footballers are in the final stages before retirement. I think the best age is 25-30 years, that's the best period. Joselu did perform well in the UEFA Nations League 2023 semi-final match against Spain. It looks like Joselu is a good replacement, but Madrid must have another alternative. It could be Kane, Mbappe and maybe Mane.
The age of 33 years is still considered young, not for a football player, for example someone who is able to hold strategic positions in government installations or is successful as an entrepreneur, that person will be said to be able to achieve success in his field at a young age. As for soccer players, the age of 33 is considered old and has passed a productive period, this age is considered the end of a player's career.
Lots of top players are starting to decline in appearance at this age so it is difficult to find a club in the elite league that will interest him. They are forced to seek their fortune in lower leagues or outside Europe in order to continue their careers before deciding to retire.
Luck is still on Joselu side because Real Madrid still have an interest in him, at least he still has the chance to play at the highest level. Joselu could not be relied on any longer when measured by his age, he was only used as an alternative or as a substitute when Real Madrid found an ideal replacement in the position left by Benzema.