In particular, a given elephant might be "more intelligent" than a human -- we just happen to have evolved from a particular niche that has rendered us bizarrely good at abstracting knowledge and combining it with the knowledge of other humans.
We have very good problem solving ability of course, but a superpowered ability to ask others how they solved the problem. If we wanted to somehow define a kind of 'brain horsepower' type intelligence, it seems to me that the former is closer to it than the latter, and it doesn't seem obvious to me that humans would necessarily take the top spot. Or that there's a reasonable/ethical way to test it -- let's take a human, elephant, crow, and dolphin, raise them in total isolation from the any community to get a measure of their untrained intelligence... we might get some interesting results on intelligence, but mostly we will learn something about ballistics as some ethics review board launches us unto the Sun.
It may be hard to measure and even define precisely, but I think it's pretty clear that if we did agree on a definition in the context of this conversation it would be defined in such a way that humans are more intelligent than elephants.
I have listened to François Chollet say that all intelligence is specialized intelligence.
I suspect the question really doesn't make sense if that is true.
We just have this bias/mind projection fallacy that intelligence is a general physical property of the brain that can be measured. I just suspect this is not true.
Like athletic ability doesn't generalize well. Of course, someone not athletic at all is never going to be a great athlete in anything but it makes no sense to compare Lance Armstrong to Patrick Mahomes in some general athletic context. Putting a number on a general athletic ability index between the two would just be total nonsense.